diff --git a/README.md b/README.md
index 4078be2..7160fa8 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,7 @@ pooling, proxies, retries, [and more](#features)!
     * [`opts.cacheManager`](#opts-cache-manager)
     * [`opts.cache`](#opts-cache)
     * [`opts.proxy`](#opts-proxy)
+    * [`opts.noProxy`](#opts-no-proxy)
     * [`opts.ca, opts.cert, opts.key`](#https-opts)
     * [`opts.maxSockets`](#opts-max-sockets)
     * [`opts.retry`](#opts-retry)
@@ -137,6 +138,7 @@ make-fetch-happen augments the `node-fetch` API with additional features availab
 * [`opts.cacheManager`](#opts-cache-manager) - Cache target to read/write
 * [`opts.cache`](#opts-cache) - `fetch` cache mode. Controls cache *behavior*.
 * [`opts.proxy`](#opts-proxy) - Proxy agent
+* [`opts.noProxy`](#opts-no-proxy) - Domain segments to disable proxying for.
 * [`opts.ca, opts.cert, opts.key, opts.strictSSL`](#https-opts)
 * [`opts.localAddress`](#opts-local-address)
 * [`opts.maxSockets`](#opts-max-sockets)
@@ -286,6 +288,13 @@ fetch('https://registry.npmjs.org/make-fetch-happen', {
 })
 ```
 
+#### <a name="opts-no-proxy"></a> `> opts.noProxy`
+
+If present, should be a comma-separated string or an array of domain extensions
+that a proxy should _not_ be used for.
+
+This option may also be provided through `process.env.NO_PROXY`.
+
 #### <a name="https-opts"></a> `> opts.ca, opts.cert, opts.key, opts.strictSSL`
 
 These values are passed in directly to the HTTPS agent and will be used for both
diff --git a/agent.js b/agent.js
index e19e5cf..fb97208 100644
--- a/agent.js
+++ b/agent.js
@@ -59,9 +59,22 @@ function getAgent (uri, opts) {
   return agent
 }
 
-function checkNoProxy (uri) {
-  // TODO
-  return false
+function checkNoProxy (uri, opts) {
+  const host = url.parse(uri).hostname.split('.').reverse()
+  let noproxy = (opts.noProxy || getProcessEnv('no_proxy'))
+  if (typeof noproxy === 'string') {
+    noproxy = noproxy.split(/\s*,\s*/g)
+  }
+  return noproxy && noproxy.some(no => {
+    const noParts = no.split('.').filter(x => x).reverse()
+    if (!noParts.length) { return false }
+    for (let i = 0; i < noParts.length; i++) {
+      if (host[i] !== noParts[i]) {
+        return false
+      }
+    }
+    return true
+  })
 }
 
 module.exports.getProcessEnv = getProcessEnv
@@ -97,10 +110,11 @@ function getProxyUri (uri, opts) {
   ) || (
     protocol === 'http:' && getProcessEnv(['https_proxy', 'http_proxy', 'proxy'])
   )
+  if (!proxy) { return null }
 
   const parsedProxy = (typeof proxy === 'string') ? url.parse(proxy) : proxy
 
-  return !checkNoProxy(uri) && parsedProxy
+  return !checkNoProxy(uri, opts) && parsedProxy
 }
 
 let HttpProxyAgent