diff --git a/execjs.gemspec b/execjs.gemspec
index a440c00..fd13f9f 100644
--- a/execjs.gemspec
+++ b/execjs.gemspec
@@ -10,17 +10,18 @@ Gem::Specification.new do |s|
   EOS
 
   s.files = [
-    "lib/execjs",
+    "lib/execjs.rb",
     "lib/execjs/external_runtime.rb",
+    "lib/execjs/rhino_runtime.rb",
     "lib/execjs/runners",
     "lib/execjs/runners/basic.js",
     "lib/execjs/runners/node.js",
     "lib/execjs/runtimes.rb",
-    "lib/execjs/v8_runtime.rb",
-    "lib/execjs.rb"
+    "lib/execjs/v8_runtime.rb"
   ]
 
   s.add_development_dependency "therubyracer"
+  s.add_development_dependency "therubyrhino"
 
   s.authors           = ["Sam Stephenson"]
   s.email             = "sstephenson@gmail.com"
diff --git a/lib/execjs.rb b/lib/execjs.rb
index e3ef4f7..f310d5d 100644
--- a/lib/execjs.rb
+++ b/lib/execjs.rb
@@ -4,6 +4,7 @@ module ExecJS
   class ProgramError    < Error; end
 
   autoload :ExternalRuntime, "execjs/external_runtime"
+  autoload :RhinoRuntime,    "execjs/rhino_runtime"
   autoload :Runtimes,        "execjs/runtimes"
   autoload :V8Runtime,       "execjs/v8_runtime"
 
diff --git a/lib/execjs/rhino_runtime.rb b/lib/execjs/rhino_runtime.rb
new file mode 100644
index 0000000..32caca2
--- /dev/null
+++ b/lib/execjs/rhino_runtime.rb
@@ -0,0 +1,46 @@
+module ExecJS
+  class RhinoRuntime
+    def initialize(options)
+    end
+
+    def exec(source)
+      if /\S/ =~ source
+        eval "(function(){#{source}})()"
+      end
+    end
+
+    def eval(source)
+      if /\S/ =~ source
+        context = ::Rhino::Context.new
+        unbox context.eval("(#{source})")
+      end
+    rescue ::Rhino::JavascriptError => e
+      if e.message == "syntax error"
+        raise RuntimeError, e
+      else
+        raise ProgramError, e
+      end
+    end
+
+    def available?
+      require "rhino"
+      true
+    rescue LoadError
+      false
+    end
+
+    def unbox(value)
+      case value
+      when ::Rhino::NativeFunction
+        nil
+      when ::Rhino::NativeObject
+        value.inject({}) do |vs, (k, v)|
+          vs[k] = unbox(v) unless v.is_a?(::Rhino::NativeFunction)
+          vs
+        end
+      else
+        value
+      end
+    end
+  end
+end
diff --git a/lib/execjs/runtimes.rb b/lib/execjs/runtimes.rb
index 9100248..3c80065 100644
--- a/lib/execjs/runtimes.rb
+++ b/lib/execjs/runtimes.rb
@@ -38,5 +38,8 @@ module ExecJS
     define_runtime :Spidermonkey,
       :command => "js",
       :runner_path => runner_path("basic.js")
+
+    define_runtime :Rhino,
+      :as => RhinoRuntime
   end
 end
diff --git a/test/test_runtimes.rb b/test/test_runtimes.rb
index ace0092..2abe829 100644
--- a/test/test_runtimes.rb
+++ b/test/test_runtimes.rb
@@ -63,3 +63,4 @@ test_runtime :ExternalV8
 test_runtime :Node
 test_runtime :JSC
 test_runtime :Spidermonkey
+test_runtime :Rhino