diff --git a/scrapy/http/__init__.py b/scrapy/http/__init__.py
index f04a9d3e5..4b2f7b33f 100644
--- a/scrapy/http/__init__.py
+++ b/scrapy/http/__init__.py
@@ -10,6 +10,7 @@ from scrapy.http.headers import Headers
 from scrapy.http.request import Request
 from scrapy.http.request.form import FormRequest
 from scrapy.http.request.rpc import XmlRpcRequest
+from scrapy.http.request.json_request import JSONRequest
 
 from scrapy.http.response import Response
 from scrapy.http.response.html import HtmlResponse
diff --git a/scrapy/http/request/json_request.py b/scrapy/http/request/json_request.py
new file mode 100644
index 000000000..0fdd2ddf1
--- /dev/null
+++ b/scrapy/http/request/json_request.py
@@ -0,0 +1,28 @@
+"""
+This module implements the JSONRequest class which is a more convenient class
+(than Request) to generate JSON Requests.
+
+See documentation in docs/topics/request-response.rst
+"""
+
+import json
+
+from scrapy.http.request import Request
+
+
+class JSONRequest(Request):
+    def __init__(self, *args, **kwargs):
+        if 'method' not in kwargs:
+            kwargs['method'] = 'POST'
+
+        data = kwargs.pop('data', {})
+        kwargs['body'] = json.dumps(data)
+        super(JSONRequest, self).__init__(*args, **kwargs)
+        self.headers.setdefault(b'Content-Type', b'application/json')
+
+    def replace(self, *args, **kwargs):
+        """ Create a new Request with the same attributes except for those
+            given new values. """
+
+        kwargs.pop('body', None)
+        return super(JSONRequest, self).replace(*args, **kwargs)
diff --git a/tests/test_http_request.py b/tests/test_http_request.py
index 58326a384..3f2e4f521 100644
--- a/tests/test_http_request.py
+++ b/tests/test_http_request.py
@@ -2,6 +2,7 @@
 import cgi
 import unittest
 import re
+import json
 
 import six
 from six.moves import xmlrpc_client as xmlrpclib
@@ -9,7 +10,7 @@ from six.moves.urllib.parse import urlparse, parse_qs, unquote
 if six.PY3:
     from urllib.parse import unquote_to_bytes
 
-from scrapy.http import Request, FormRequest, XmlRpcRequest, Headers, HtmlResponse
+from scrapy.http import Request, FormRequest, XmlRpcRequest, JSONRequest, Headers, HtmlResponse
 from scrapy.utils.python import to_bytes, to_native_str
 
 
@@ -1147,5 +1148,57 @@ class XmlRpcRequestTest(RequestTest):
         self._test_request(params=(u'pas£',), encoding='latin1')
 
 
+class JSONRequestTest(RequestTest):
+    request_class = JSONRequest
+    default_method = 'POST'
+    default_headers = {b'Content-Type': [b'application/json']}
+
+    def test_body(self):
+        r1 = self.request_class(url="http://www.example.com/")
+        self.assertEqual(r1.body, '{}')
+
+        r2 = self.request_class(url="http://www.example.com/", body=b"")
+        self.assertEqual(r2.body, '{}')
+
+        data = {
+            'name': 'value',
+        }
+        r3 = self.request_class(url="http://www.example.com/", data=data)
+        self.assertEqual(r3.body, json.dumps(data))
+
+        r4 = self.request_class(url="http://www.example.com/", body='body1', data=data)
+        self.assertEqual(r3.body, json.dumps(data))
+
+    def test_replace(self):
+        """Test Request.replace() method"""
+        r1 = self.request_class("http://www.example.com")
+        hdrs = Headers(r1.headers)
+        hdrs[b'key'] = b'value'
+        r2 = r1.replace(body="New body", headers=hdrs)
+
+        # body will not be replaced
+        self.assertEqual(r1.body, r2.body)
+        self.assertEqual(r1.url, r2.url)
+        self.assertEqual((r1.headers, r2.headers), (self.default_headers, hdrs))
+
+        # Empty attributes (which may fail if not compared properly)
+        r3 = self.request_class("http://www.example.com", meta={'a': 1}, dont_filter=True)
+        r4 = r3.replace(url="http://www.example.com/2", meta={}, dont_filter=False)
+        self.assertEqual(r4.url, "http://www.example.com/2")
+        self.assertEqual(r4.meta, {})
+        assert r4.dont_filter is False
+
+        data1 = {
+            'name': 'value1',
+        }
+        data2 = {
+            'name': 'value2',
+        }
+        r5 = self.request_class("http://www.example.com", data=data1)
+        r6 = r5.replace(url="http://www.example.com/2", data=data2)
+        self.assertNotEqual(r5.body, r6.body)
+        self.assertEqual((r5.body, r6.body), (json.dumps(data1), json.dumps(data2)))
+
+
 if __name__ == "__main__":
     unittest.main()