diff --git a/Gemfile b/Gemfile
index d5a9b82..ccbbc00 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,3 +2,10 @@ source 'https://rubygems.org'
 
 # Specify your gem's dependencies in pact.gemspec
 gemspec
+
+group :test do
+  gem 'faraday', '~> 2.0'
+  gem 'faraday-retry', '~> 2.0'
+  gem 'webrick', '~> 1.8'
+  gem 'rack', '~> 2.2'
+end
diff --git a/lib/pact/consumer_contract/pact_file.rb b/lib/pact/consumer_contract/pact_file.rb
index 20c7042..b54d096 100644
--- a/lib/pact/consumer_contract/pact_file.rb
+++ b/lib/pact/consumer_contract/pact_file.rb
@@ -109,6 +109,12 @@ def prepare_request(uri, options)
       http.ca_file = ENV['SSL_CERT_FILE'] if ENV['SSL_CERT_FILE'] && ENV['SSL_CERT_FILE'] != ''
       http.ca_path = ENV['SSL_CERT_DIR'] if ENV['SSL_CERT_DIR'] && ENV['SSL_CERT_DIR'] != ''
       http.set_debug_output(Pact::Http::AuthorizationHeaderRedactor.new(Pact.configuration.output_stream)) if verbose?(options)
+
+      if x509_certificate?
+        http.cert = OpenSSL::X509::Certificate.new(x509_client_cert_file)
+        http.key = OpenSSL::PKey::RSA.new(x509_client_key_file)
+      end
+
       if disable_ssl_verification?
         if verbose?(options)
           Pact.configuration.output_stream.puts("SSL verification is disabled")
@@ -150,6 +156,19 @@ def verbose?(options)
       options[:verbose] || ENV['VERBOSE'] == 'true'
     end
 
+    def x509_certificate?
+      ENV['X509_CLIENT_CERT_FILE'] && ENV['X509_CLIENT_CERT_FILE'] != '' &&
+        ENV['X509_CLIENT_KEY_FILE'] && ENV['X509_CLIENT_KEY_FILE'] != ''
+    end
+
+    def x509_client_cert_file
+      File.read(ENV['X509_CLIENT_CERT_FILE'])
+    end
+
+    def x509_client_key_file
+      File.read(ENV['X509_CLIENT_KEY_FILE'])
+    end
+
     def disable_ssl_verification?
       ENV['PACT_DISABLE_SSL_VERIFICATION'] == 'true' || ENV['PACT_BROKER_DISABLE_SSL_VERIFICATION'] == 'true'
     end
diff --git a/spec/fixtures/certificates/ca_cert.pem b/spec/fixtures/certificates/ca_cert.pem
new file mode 100644
index 0000000..ad49d99
--- /dev/null
+++ b/spec/fixtures/certificates/ca_cert.pem
@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE-----
+MIIDATCCAemgAwIBAgIUWfQF2Mh+eFd3q+cSVgekpaMTh9MwDQYJKoZIhvcNAQEL
+BQAwDzENMAsGA1UEAwwETXlDQTAgFw0yMzA5MTkxMTA2MjZaGA8yMTIzMDgyNjEx
+MDYyNlowDzENMAsGA1UEAwwETXlDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCC
+AQoCggEBAK9Qha2OdeFrSCUqiYRUBngNLn8PRGDaKPWmjd+3WOWJNM1RNgFfGpKY
+nxYJp4J6eW7aeQ6o94Q+QOZp+Yxm6thrtvjRbcEafAore4EwC4tjXvoFoy+mKwzm
+njlJw+ha3TsMAqD3GGDLF7uDnmliURRo8TOmJ++Mwss9Uhb5p9LArjWXa3sV8da+
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+gBzicV1PPDkmkbxKmFV+D8LmkwWNsRhrzZ6TIxYoXIRhziS7JuYOGU7G0+6ZKpIP
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+c3U03pPKCnvsG5z60ZgmNSqzyVAVPW17UVdw/ZnkKK/SFxYgYQaF/1g6opS2Zana
+4aBGypqqGoD4KE+DAnRjuuCUpiz3zXwGd86auajY6soMlLNnVXteVa/whW6IZ84x
+w4LISeMGUr+MXw9ye4WhcZYKZ4vwJdUYst2PA0pDuGwBDbGnrYloGm2BSpaHXUUo
+XrwKFFkIxcK63IpAhoceTJpyfjI1BSmItfjEwToOUu6xDBsHLNiH6BKstSxk0DfX
+01PHz2I=
+-----END CERTIFICATE-----
diff --git a/spec/fixtures/certificates/ca_cert.srl b/spec/fixtures/certificates/ca_cert.srl
new file mode 100644
index 0000000..5a95107
--- /dev/null
+++ b/spec/fixtures/certificates/ca_cert.srl
@@ -0,0 +1 @@
+494F82D5FE5055D2C9C64941C421085B59521071
diff --git a/spec/fixtures/certificates/ca_key.pem b/spec/fixtures/certificates/ca_key.pem
new file mode 100644
index 0000000..c29f42e
--- /dev/null
+++ b/spec/fixtures/certificates/ca_key.pem
@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----
+MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQCvUIWtjnXha0gl
+KomEVAZ4DS5/D0Rg2ij1po3ft1jliTTNUTYBXxqSmJ8WCaeCenlu2nkOqPeEPkDm
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+jdz8n6cimYuSRwrjmt3VmqrNLL4+0ARMsptV/Yt++TdmxY3puUFsZevN6hGfGxT6
+/6GXikkIIpKWYQETjCjWpcJFdqyc6C6aCPoxd5UCgYEA1B4AdDgxhZgXhz24sKM7
+aX2aY4glBsEZ7dxaqpqvwmsSshvdfudjuFxo5jjMKV2C9JmwrCGML9O6MvSP03n8
+B3R543JqKqWLTaSROHkcoil+LdIV9w7jrMBildOCHSDXwuM8Pl7YObIdKMq4pVwe
+87n9/ZihlrKGaZ8utMrrGmc=
+-----END PRIVATE KEY-----
diff --git a/spec/fixtures/certificates/client_cert.pem b/spec/fixtures/certificates/client_cert.pem
new file mode 100644
index 0000000..c97f425
--- /dev/null
+++ b/spec/fixtures/certificates/client_cert.pem
@@ -0,0 +1,17 @@
+-----BEGIN CERTIFICATE-----
+MIICrDCCAZQCFElPgtX+UFXSycZJQcQhCFtZUhBxMA0GCSqGSIb3DQEBCwUAMA8x
+DTALBgNVBAMMBE15Q0EwIBcNMjMwOTE5MTEwNzM1WhgPMjEyMzA4MjYxMTA3MzVa
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+fvyYdnoNLP0YeRI6j9x1pg==
+-----END CERTIFICATE-----
diff --git a/spec/fixtures/certificates/key.pem b/spec/fixtures/certificates/key.pem
new file mode 100644
index 0000000..e0879e3
--- /dev/null
+++ b/spec/fixtures/certificates/key.pem
@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----
+MIIEvAIBADANBgkqhkiG9w0BAQEFAASCBKYwggSiAgEAAoIBAQCY+gxfm7tA4V5p
+AWgtvgpKKjZbDvi81vW2ZzQkJNCcPfX4Ahky4n1NzXsgISoB7Pldxv/VC2zK8WDE
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+uPaEN0rPMT6wMEegJHaE8A==
+-----END PRIVATE KEY-----
diff --git a/spec/fixtures/certificates/server.csr b/spec/fixtures/certificates/server.csr
new file mode 100644
index 0000000..d8020bb
--- /dev/null
+++ b/spec/fixtures/certificates/server.csr
@@ -0,0 +1,15 @@
+-----BEGIN CERTIFICATE REQUEST-----
+MIICWTCCAUECAQAwFDESMBAGA1UEAwwJbG9jYWxob3N0MIIBIjANBgkqhkiG9w0B
+AQEFAAOCAQ8AMIIBCgKCAQEAmPoMX5u7QOFeaQFoLb4KSio2Ww74vNb1tmc0JCTQ
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+2gaBXdvbabkXKAHnV0tYbDmZXvTO+7Ci7wgapNU=
+-----END CERTIFICATE REQUEST-----
diff --git a/spec/fixtures/certificates/unsigned_cert.pem b/spec/fixtures/certificates/unsigned_cert.pem
new file mode 100644
index 0000000..ea78712
--- /dev/null
+++ b/spec/fixtures/certificates/unsigned_cert.pem
@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE-----
+MIIDCzCCAfOgAwIBAgIUN2/oKOttkdOretzyqc+Zv8IqpT8wDQYJKoZIhvcNAQEL
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+2cylIQmuuNIRGLmCRsVK
+-----END CERTIFICATE-----
diff --git a/spec/fixtures/certificates/unsigned_key.pem b/spec/fixtures/certificates/unsigned_key.pem
new file mode 100644
index 0000000..c7fab0c
--- /dev/null
+++ b/spec/fixtures/certificates/unsigned_key.pem
@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----
+MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQD30tqrKrHa0p1R
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+1We7LoJVUwKBgQCnF1qtH5d0ukPTEdC73Q0z/buM7tPKRMTqXHxxPQN9782tVDYf
+nAlWiVTENqpoUM4fxKq/SSL+SvfhyvrMW/z8NLi2bDUpEzviufg58N+v60dOeFyC
+hgiSLgYGUfweeGrPx6qymGxo7SCWSLtrjhqZB/UIAADnTAeTcOKGhECQHQKBgAlM
+A29J+BuBZMzK87CJIjbeRaVrmvSjXdeMzd+o+01ratn9bjwO14SRTfvhlbRzLLLO
+y78YmutZbuZuWY5p5pUjJ9uv2o/INr3vnV0NqM4yVx8Vr/YoOnCkHGAKf4iVs8bw
+E/b/8RHmOOvgSjjbvIKY8E1jMH8Az2e0CfqYyOBdAoGAOlhTefyBGgAWFHqH/l4p
+ThbWupIMsw1ZXlArwBnTfsUFuz0Yq7B+0tqrV8lhS3P4/0jI2yWnzhluDk62clwz
+Xg187V85Ylagshsjv60mP5qBEF4N7Nf5fP2w6+GjMU+YiHEBsgGGt+2jPgKeCGQW
+IlV3ym59oL+wGyN9OK3z+aw=
+-----END PRIVATE KEY-----
diff --git a/spec/lib/pact/consumer_contract/pact_file_spec.rb b/spec/lib/pact/consumer_contract/pact_file_spec.rb
index 3608f6d..a032ddc 100644
--- a/spec/lib/pact/consumer_contract/pact_file_spec.rb
+++ b/spec/lib/pact/consumer_contract/pact_file_spec.rb
@@ -2,6 +2,8 @@
 require 'tempfile'
 require 'pact/consumer_contract/pact_file'
 require 'base64' # XXX: https://github.com/bblimke/webmock/pull/611
+require "faraday"
+require "faraday/retry"
 
 module Pact
   describe PactFile do
@@ -212,6 +214,80 @@ def render_pact(options = {})
           end
         end
       end
+
+      describe "x509 certificate" do
+        FAKE_SERVER_URL = 'https://localhost:4444'
+        X509_CERT_FILE_PATH = './spec/fixtures/certificates/client_cert.pem'
+        X509_KEY_FILE_PATH = './spec/fixtures/certificates/key.pem'
+        UNSIGNED_X509_CERT_FILE_PATH = './spec/fixtures/certificates/unsigned_cert.pem'
+        UNSIGNED_X509_KEY_FILE_PATH = './spec/fixtures/certificates/unsigned_key.pem'
+
+        def wait_for_server_to_start
+          Faraday.new(
+            url: FAKE_SERVER_URL,
+            ssl: {
+              verify: false,
+              client_cert: OpenSSL::X509::Certificate.new(File.read(X509_CERT_FILE_PATH)),
+              client_key: OpenSSL::PKey::RSA.new(File.read(X509_KEY_FILE_PATH))
+            }
+          ) do |builder|
+            builder.request :retry, max: 20, interval: 0.5, exceptions: [StandardError]
+            builder.adapter :net_http
+          end.get
+        end
+
+        let(:render_pact) { PactFile.render_pact(FAKE_SERVER_URL, {}) }
+
+        before(:all) do
+          @pipe = IO.popen("bundle exec ruby ./spec/support/ssl_server.rb")
+          ENV['SSL_CERT_FILE'] = "./spec/fixtures/certificates/ca_cert.pem"
+
+          wait_for_server_to_start()
+        end
+
+        context "with valid x509 client certificates" do
+          before do
+            ENV['X509_CLIENT_CERT_FILE'] = X509_CERT_FILE_PATH
+            ENV['X509_CLIENT_KEY_FILE'] = X509_KEY_FILE_PATH
+          end
+
+          it "succeeds" do
+            expect(render_pact).to eq("Fake SSL server\n")
+          end
+        end
+
+        context "when invalid x509 certificates are set" do
+          before do
+            ENV['X509_CLIENT_CERT_FILE'] = UNSIGNED_X509_CERT_FILE_PATH
+            ENV['X509_CLIENT_KEY_FILE'] = UNSIGNED_X509_KEY_FILE_PATH
+          end
+
+          it "fails raising SSL error" do
+            expect { render_pact }
+              .to raise_error { |error|
+                expect([OpenSSL::SSL::SSLError, Errno::ECONNRESET]).to include(error.class)
+              }
+          end
+        end
+
+        context "when no x509 certificates are set" do
+          before do
+            ENV['X509_CLIENT_CERT_FILE'] = nil
+            ENV['X509_CLIENT_KEY_FILE'] = nil
+          end
+
+          it "fails raising SSL error" do
+            expect { render_pact }
+              .to raise_error { |error|
+                expect([OpenSSL::SSL::SSLError, Errno::ECONNRESET]).to include(error.class)
+              }
+          end
+        end
+
+        after(:all) do
+          Process.kill "KILL", @pipe.pid
+        end
+      end
     end
   end
 end
diff --git a/spec/support/ssl_server.rb b/spec/support/ssl_server.rb
new file mode 100644
index 0000000..f586de9
--- /dev/null
+++ b/spec/support/ssl_server.rb
@@ -0,0 +1,42 @@
+if __FILE__ == $0
+
+  SSL_KEY = "spec/fixtures/certificates/key.pem"
+  SSL_CERT = "spec/fixtures/certificates/client_cert.pem"
+  SSL_CA_CERT = "spec/fixtures/certificates/ca_cert.pem"
+
+  trap(:INT) do
+    @server.shutdown
+    exit
+  end
+
+  def webrick_opts port
+    certificate = OpenSSL::X509::Certificate.new(File.read(SSL_CERT))
+    cert_name = certificate.subject.to_a.collect{|a| a[0..1] }
+    logger_stream = ENV["DEBUG"] ? $stderr : StringIO.new
+    {
+      Port: port,
+      Host: "0.0.0.0",
+      AccessLog: [],
+      Logger: WEBrick::Log.new(logger_stream,WEBrick::Log::INFO),
+      SSLVerifyClient: OpenSSL::SSL::VERIFY_FAIL_IF_NO_PEER_CERT | OpenSSL::SSL::VERIFY_PEER,
+      SSLCACertificateFile: SSL_CA_CERT,
+      SSLCertificate: certificate,
+      SSLPrivateKey: OpenSSL::PKey::RSA.new(File.read(SSL_KEY)),
+      SSLEnable: true,
+      SSLCertName: cert_name,
+    }
+  end
+
+  app = ->(_env) { puts "hello"; [200, {}, ["Fake SSL server" + "\n"]] }
+
+  require "webrick"
+  require "webrick/https"
+  require "rack"
+  require "rack/handler/webrick"
+
+  opts = webrick_opts(4444)
+
+  Rack::Handler::WEBrick.run(app, **opts) do |server|
+    @server = server
+  end
+end