diff --git a/lib/fog/aws/parsers/sts/assume_role_with_saml.rb b/lib/fog/aws/parsers/sts/assume_role_with_saml.rb
new file mode 100644
index 000000000..34ade15b8
--- /dev/null
+++ b/lib/fog/aws/parsers/sts/assume_role_with_saml.rb
@@ -0,0 +1,26 @@
+module Fog
+  module Parsers
+    module AWS
+      module STS
+        class AssumeRoleWithSAML < Fog::Parsers::Base
+          def reset
+            @response = {}
+          end
+
+          def end_element(name)
+            case name
+            when 'SessionToken', 'SecretAccessKey', 'Expiration', 'AccessKeyId'
+              @response[name] = @value.strip
+            when 'Arn', 'AssumedRoleId'
+              @response[name] = @value.strip
+            when 'PackedPolicySize'
+              @response[name] = @value
+            when 'RequestId'
+              @response[name] = @value
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/fog/aws/requests/sts/assume_role_with_saml.rb b/lib/fog/aws/requests/sts/assume_role_with_saml.rb
new file mode 100644
index 000000000..9d0665ee6
--- /dev/null
+++ b/lib/fog/aws/requests/sts/assume_role_with_saml.rb
@@ -0,0 +1,44 @@
+module Fog
+  module AWS
+    class STS
+      class Real
+        require 'fog/aws/parsers/sts/assume_role_with_saml'
+
+        # Assume Role with SAML
+        #
+        # ==== Parameters
+        # * role_arn<~String> - The ARN of the role the caller is assuming.
+        # * principal_arn<~String> - The Amazon Resource Name (ARN) of the SAML provider in IAM that describes the IdP.
+        # * saml_assertion<~String> - The base-64 encoded SAML authentication response provided by the IdP.
+        # * policy<~String> - An optional JSON policy document
+        # * duration<~Integer> - Duration (of seconds) for the assumed role credentials to be valid (default 3600)
+        #
+        # ==== Returns
+        # * response<~Excon::Response>:
+        #   * body<~Hash>:
+        #     * 'Arn'<~String>: The ARN of the assumed role/user
+        #     * 'AccessKeyId'<~String>: The AWS access key of the temporary credentials for the assumed role
+        #     * 'SecretAccessKey'<~String>: The AWS secret key of the temporary credentials for the assumed role
+        #     * 'SessionToken'<~String>: The AWS session token of the temporary credentials for the assumed role
+        #     * 'Expiration'<~Time>: The expiration time of the temporary credentials for the assumed role
+        #
+        # ==== See Also
+        # http://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithSAML.html
+        #
+
+        def assume_role_with_saml(role_arn, principal_arn, saml_assertion, policy=nil, duration=3600)
+          request_unsigned({
+            'Action'          => 'AssumeRoleWithSAML',
+            'RoleArn'         => role_arn,  
+            'PrincipalArn'    => principal_arn,
+            'SAMLAssertion'   => saml_assertion,
+            'Policy'          => policy && Fog::JSON.encode(policy),
+            'DurationSeconds' => duration,
+            :idempotent       => true,
+            :parser           => Fog::Parsers::AWS::STS::AssumeRoleWithSAML.new
+          })
+        end
+      end
+    end
+  end
+end
diff --git a/lib/fog/aws/sts.rb b/lib/fog/aws/sts.rb
index c5c0b8ca7..8391c67bb 100644
--- a/lib/fog/aws/sts.rb
+++ b/lib/fog/aws/sts.rb
@@ -7,14 +7,15 @@ module Fog
 
       class EntityAlreadyExists < Fog::AWS::STS::Error; end
       class ValidationError < Fog::AWS::STS::Error; end
+      class AwsAccessKeysMissing < Fog::AWS::STS::Error; end
 
-      requires :aws_access_key_id, :aws_secret_access_key
-      recognizes :host, :path, :port, :scheme, :persistent, :aws_session_token, :use_iam_profile, :aws_credentials_expire_at, :instrumentor, :instrumentor_name
+      recognizes :aws_access_key_id, :aws_secret_access_key, :host, :path, :port, :scheme, :persistent, :aws_session_token, :use_iam_profile, :aws_credentials_expire_at, :instrumentor, :instrumentor_name
 
       request_path 'fog/aws/requests/sts'
       request :get_federation_token
       request :get_session_token
       request :assume_role
+      request :assume_role_with_saml
 
       class Mock
         def self.data
@@ -99,10 +100,16 @@ module Fog
           @aws_session_token      = options[:aws_session_token]
           @aws_credentials_expire_at = options[:aws_credentials_expire_at]
 
-          @signer = Fog::AWS::SignatureV4.new(@aws_access_key_id, @aws_secret_access_key, 'us-east-1', 'sts')
+          if (@aws_access_key_id && @aws_secret_access_key)
+            @signer = Fog::AWS::SignatureV4.new(@aws_access_key_id, @aws_secret_access_key, 'us-east-1', 'sts')
+          end
         end
 
         def request(params)
+          if (@signer == nil)
+            raise AwsAccessKeysMissing.new("Can't make unsigned requests, need aws_access_key_id and aws_secret_access_key")
+          end
+
           idempotent  = params.delete(:idempotent)
           parser      = params.delete(:parser)
 
@@ -129,6 +136,30 @@ module Fog
           end
         end
 
+        def request_unsigned(params)
+          idempotent  = params.delete(:idempotent)
+          parser      = params.delete(:parser)
+
+          params['Version'] = '2011-06-15'
+
+          headers = { 'Content-Type' => 'application/x-www-form-urlencoded', 'Host' => @host }
+          body = ''
+          for key in params.keys.sort
+            unless (value = params[key]).nil?
+              body << "#{key}=#{Fog::AWS.escape(value.to_s)}&"
+            end
+          end
+          body.chop!
+
+          if @instrumentor
+            @instrumentor.instrument("#{@instrumentor_name}.request", params) do
+              _request(body, headers, idempotent, parser)
+            end
+          else
+            _request(body, headers, idempotent, parser)
+          end
+        end
+
         def _request(body, headers, idempotent, parser)
           @connection.request({
             :body       => body,
diff --git a/tests/aws/requests/sts/assume_role_with_saml_tests.rb b/tests/aws/requests/sts/assume_role_with_saml_tests.rb
new file mode 100644
index 000000000..e482365d6
--- /dev/null
+++ b/tests/aws/requests/sts/assume_role_with_saml_tests.rb
@@ -0,0 +1,18 @@
+Shindo.tests('AWS::STS | assume role with SAML', ['aws']) do
+
+	@policy = {"Statement" => [{"Effect" => "Allow", "Action" => "*", "Resource" => "*"}]}
+
+	@response_format = {
+		'SessionToken' => String,
+		'SecretAccessKey' => String,
+		'Expiration' => String,
+		'AccessKeyId' => String,
+		'Arn' => String,
+		'RequestId' => String
+	}
+
+	tests("#assume_role_with_saml('role_arn', 'principal_arn', 'saml_assertion', #{@policy.inspect}, 900)").formats(@response_format) do
+		pending if Fog.mocking?
+		Fog::AWS[:sts].assume_role_with_saml("role_arn","principal_arn","saml_assertion", @policy, 900).body
+	end
+end