 <p>Yes, you can send a <code>GET</code> request with no query string. In fact, whenever you hit a webpage using with your browser, you <em>are</em> sending a <code>GET</code> request, e.g. when you type <code>http://google.com</code> in the address bar and hit enter, your browser sends <code>GET</code> request to the URI and google server returns its page.</p> <p>As Mardzis noted in comments, you can use <code>empty()</code> function in your PHP code:</p> <pre><code>&lt;?php if (!empty($_GET['query'])) { $query = $_GET['query']; // Return results for specific query... } else { // Return all results... } </code></pre> <p><strong>EDIT</strong></p> <p>Since you've posted your Javascript code, I noticed something:</p> <pre><code>function showResults(str) { if (str.length == 0) { // If str is empty - isn't this where you want your "empty" query? But you don't } else { // If str is not empty, you send the request. } </code></pre> <p>Seems like if <code>str</code> is empty, you're not sending the request at all. Am I correct?</p>