diff --git a/README.md b/README.md
index 58f7e36..0e30493 100644
--- a/README.md
+++ b/README.md
@@ -100,7 +100,7 @@ Mock a low level network error
 // Returns a failed promise with Error('Network Error');
 mock.onGet('/users').networkError();
 
-// networkErrorOnce can be used to mock a network error only once 
+// networkErrorOnce can be used to mock a network error only once
 mock.onGet('/users').networkErrorOnce();
 ```
 
@@ -110,7 +110,7 @@ Mock a network timeout
 // Returns a failed promise with Error with code set to 'ECONNABORTED'
 mock.onGet('/users').timeout();
 
-// timeoutOnce can be used to mock a timeout only once 
+// timeoutOnce can be used to mock a timeout only once
 mock.onGet('/users').timeoutOnce();
 ```
 
@@ -245,6 +245,17 @@ mock
 
 Note that `passThrough` requests are not subject to delaying by `delayResponse`.
 
+If you set `passThroughByDefault` option all requests would be forwarded over network by default
+
+```js
+// Mock all requests to /foo with HTTP 200, but forward
+// any others requests to server
+var mock = new MockAdapter(axiosInstance, { passThroughByDefault: true });
+
+mock
+  .onAny('/foo').reply(200);
+```
+
 As of 1.7.0, `reply` function may return a Promise:
 
 ```js
diff --git a/src/handle_request.js b/src/handle_request.js
index 7ad2bb0..d343773 100644
--- a/src/handle_request.js
+++ b/src/handle_request.js
@@ -76,15 +76,19 @@ function handleRequest(mockAdapter, resolve, reject, config) {
     }
   } else {
     // handler not found
-    utils.settle(
-      resolve,
-      reject,
-      {
-        status: 404,
-        config: config
-      },
-      mockAdapter.delayResponse
-    );
+    if (mockAdapter.passThroughByDefault) {
+      mockAdapter.originalAdapter(config).then(resolve, reject);
+    } else {
+      utils.settle(
+        resolve,
+        reject,
+        {
+          status: 404,
+          config: config
+        },
+        mockAdapter.delayResponse
+      );
+    }
   }
 }
 
diff --git a/src/index.js b/src/index.js
index 5c91363..9c76c07 100644
--- a/src/index.js
+++ b/src/index.js
@@ -49,6 +49,7 @@ function MockAdapter(axiosInstance, options) {
     this.axiosInstance = axiosInstance;
     this.originalAdapter = axiosInstance.defaults.adapter;
     this.delayResponse = options && options.delayResponse > 0 ? options.delayResponse : null;
+    this.passThroughByDefault = !!(options && options.passThroughByDefault);
     axiosInstance.defaults.adapter = this.adapter.call(this);
   }
 }
diff --git a/test/pass_through_by_default.spec.js b/test/pass_through_by_default.spec.js
new file mode 100644
index 0000000..85b71a9
--- /dev/null
+++ b/test/pass_through_by_default.spec.js
@@ -0,0 +1,161 @@
+var axios = require('axios');
+var expect = require('chai').expect;
+var createServer = require('http').createServer;
+
+var MockAdapter = require('../src');
+
+describe('passThroughByDefault option tests (requires Node)', function() {
+  var instance;
+  var mock;
+  var httpServer;
+  var serverUrl;
+
+  before('set up Node server', function() {
+    return new Promise(function(resolve, reject) {
+      httpServer = createServer(function(req, resp) {
+        if (req.url === '/error') {
+          resp.statusCode = 500;
+          resp.end();
+        } else {
+          resp.statusCode = 200;
+          // Reply with path
+          resp.end(req.url, 'utf8');
+        }
+      })
+        .listen(0, '127.0.0.1', function() {
+          serverUrl = 'http://127.0.0.1:' + httpServer.address().port;
+          resolve();
+        })
+        .on('error', reject);
+    });
+  });
+
+  after(function() {
+    httpServer.close();
+  });
+
+  beforeEach(function() {
+    instance = axios.create({ baseURL: serverUrl });
+    mock = new MockAdapter(instance, { passThroughByDefault: true });
+  });
+
+  it('works correctly if set no handlers', function() {
+    var randomPath = 'xyz' + Math.round(10000 * Math.random());
+
+    return Promise.all([
+      instance.get('/' + randomPath).then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('/' + randomPath);
+      })
+    ]);
+  });
+
+  it('allows selective mocking', function() {
+    mock.onGet('/foo').reply(200, 'bar');
+    mock.onGet('/error').reply(200, 'success');
+    mock.onGet('/bar').passThrough();
+
+    var randomPath = 'xyz' + Math.round(10000 * Math.random());
+
+    return Promise.all([
+      instance.get('/foo').then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('bar');
+      }),
+      instance.get('/error').then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('success');
+      }),
+      instance.get('/bar').then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('/bar');
+      }),
+      instance.get('/' + randomPath).then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('/' + randomPath);
+      })
+    ]);
+  });
+
+  it('handles errors correctly', function() {
+    return instance
+      .get('/error')
+      .then(function() {
+        // The server should've returned an error
+        expect(false).to.be.true;
+      })
+      .catch(function(error) {
+        expect(error).to.have.nested.property('response.status', 500);
+      });
+  });
+
+  it('setting passThrough handler don\'t break anything', function() {
+    mock
+      .onGet('/foo')
+      .reply(200, 'bar')
+      .onAny()
+      .passThrough();
+
+    var randomPath = 'xyz' + Math.round(10000 * Math.random());
+
+    return Promise.all([
+      instance.get('/foo').then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('bar');
+      }),
+      instance.get('/' + randomPath).then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('/' + randomPath);
+      }),
+      instance.post('/post').then(function(response) {
+        expect(response.status).to.equal(200);
+        expect(response.data).to.equal('/post');
+      })
+    ]);
+  });
+
+  it('handles baseURL correctly', function() {
+    instance = axios.create({
+      baseURL: '/test',
+      proxy: {
+        host: '127.0.0.1',
+        port: httpServer.address().port
+      }
+    });
+    mock = new MockAdapter(instance, { passThroughByDefault: true });
+
+    return instance.get('/foo').then(function(response) {
+      expect(response.status).to.equal(200);
+      expect(response.data).to.equal('http://null/test/foo');
+    });
+  });
+
+  it('handles request transformations properly', function() {
+    return instance
+      .get('/foo', {
+        data: 'foo',
+        transformRequest: [
+          function(data) {
+            return data + 'foo';
+          }
+        ]
+      })
+      .then(function(response) {
+        expect(response.config.data).to.equal('foofoo');
+      });
+  });
+
+  it('handles response transformations properly', function() {
+    return instance
+      .get('/foo', {
+        transformResponse: [
+          function(data) {
+            return data + 'foo';
+          }
+        ]
+      })
+      .then(function(response) {
+        expect(response.data).to.equal('/foofoo');
+      });
+  });
+});
diff --git a/types/index.d.ts b/types/index.d.ts
index c070869..3b598b5 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -22,6 +22,7 @@ interface RequestHandler {
 
 interface MockAdapterOptions {
   delayResponse?: number;
+  passThroughByDefault?: boolean;
 }
 
 interface RequestDataMatcher {
diff --git a/types/test.ts b/types/test.ts
index 60998ef..bd348d9 100644
--- a/types/test.ts
+++ b/types/test.ts
@@ -10,7 +10,8 @@ namespace AllowsConstructing {
 
 namespace AllowsConstructingWithOptions {
   new MockAdapter(instance, {
-    delayResponse: 2000
+    delayResponse: 2000,
+    passThroughByDefault: true
   });
 }