diff --git a/src/vaadin-combo-box-mixin.html b/src/vaadin-combo-box-mixin.html
index 981e164b..8909ea0f 100644
--- a/src/vaadin-combo-box-mixin.html
+++ b/src/vaadin-combo-box-mixin.html
@@ -934,6 +934,7 @@
     /** @private */
     _detectAndDispatchChange() {
       if (this.value !== this._lastCommittedValue) {
+        this.validate();
         this.dispatchEvent(new CustomEvent('change', {bubbles: true}));
         this._lastCommittedValue = this.value;
       }
@@ -1098,6 +1099,7 @@
       }
       if (!this.readonly && !this._closeOnBlurIsPrevented) {
         this._closeOrCommit();
+        this.validate();
       }
     }
 
@@ -1164,8 +1166,8 @@
      * @return {boolean | undefined}
      */
     checkValidity() {
-      if (this.inputElement.validate) {
-        return this.inputElement.validate();
+      if (this.inputElement.checkValidity) {
+        return this.inputElement.checkValidity();
       }
     }
 
diff --git a/src/vaadin-combo-box.html b/src/vaadin-combo-box.html
index a375f61a..4d26d6ce 100644
--- a/src/vaadin-combo-box.html
+++ b/src/vaadin-combo-box.html
@@ -387,6 +387,13 @@
         ready() {
           super.ready();
 
+          // Disable the internal text-field's validation to prevent it from overriding
+          // the invalid state that was propagated to the text-field from the combo-box.
+          this.inputElement.validate = () => {};
+          // Restore the internal text-field's invalid state in case
+          // it got overridden before the validation was disabled above.
+          this.inputElement.invalid = this.invalid;
+
           this._nativeInput = this.inputElement.focusElement;
           this._toggleElement = this.$.toggleButton;
           this._clearElement = this.inputElement.shadowRoot.querySelector('[part="clear-button"]');
diff --git a/test/validation.html b/test/validation.html
index 6cbd9bfa..6fd41cfb 100644
--- a/test/validation.html
+++ b/test/validation.html
@@ -7,6 +7,7 @@
 
   <script src="../../web-component-tester/browser.js"></script>
   <script src='../../webcomponentsjs/webcomponents-lite.js'></script>
+  <link rel="import" href="../../iron-test-helpers/mock-interactions.html">
   <link rel="import" href="../src/vaadin-combo-box.html">
   <link rel="import" href="helpers.html">
   <link rel="import" href="../../test-fixture/test-fixture.html">
@@ -15,10 +16,30 @@
 <body>
   <test-fixture id="combo-box">
     <template>
-      <vaadin-combo-box></vaadin-combo-box>
+      <vaadin-combo-box items='["foo"]'></vaadin-combo-box>
     </template>
   </test-fixture>
+  <test-fixture id="combo-box-required">
+    <template>
+      <vaadin-combo-box required items='["foo"]'></vaadin-combo-box>
+    </template>
+  </test-fixture>
+  <test-fixture id="combo-box-required-value-invalid">
+    <template>
+      <vaadin-combo-box required items='["foo"]' value="foo" invalid></vaadin-combo-box>
+    </template>
+  </test-fixture>
+
   <script>
+  function outsideClick() {
+    // Move focus to body
+    document.body.tabIndex = 0;
+    document.body.focus();
+    document.body.tabIndex = -1;
+    // Outside click
+    document.body.click();
+  }
+
   describe('initial validation', () => {
     let comboBox;
     let validateSpy;
@@ -54,11 +75,54 @@
       expect(validateSpy.called).to.be.false;
     });
   });
+
   describe('basic', () => {
-    let comboBox;
+    let comboBox, validateSpy, changeSpy;
 
     beforeEach(() => {
       comboBox = fixture('combo-box');
+      validateSpy = sinon.spy(comboBox, 'validate');
+      changeSpy = sinon.spy();
+      comboBox.addEventListener('change', changeSpy);
+    });
+
+    it('should disable validation of internal text-field', () => {
+      comboBox.required = true;
+      comboBox.inputElement.validate();
+      expect(comboBox.inputElement.invalid).to.be.false;
+    });
+
+    it('should validate on blur', () => {
+      comboBox.focus();
+      comboBox.blur();
+      expect(validateSpy.calledOnce).to.be.true;
+    });
+
+    it('should validate on outside click', async() => {
+      comboBox.focus();
+      comboBox.click();
+      await nextRender();
+      outsideClick();
+      expect(validateSpy.calledOnce).to.be.true;
+    });
+
+    it('should validate before change event on Enter', () => {
+      comboBox.focus();
+      comboBox.inputElement.value = 'foo';
+      comboBox.inputElement.dispatchEvent(new CustomEvent('input'));
+      MockInteractions.pressAndReleaseKeyOn(comboBox.inputElement, 13, null, 'Enter');
+      expect(validateSpy.calledOnce).to.be.true;
+      expect(changeSpy.calledOnce).to.be.true;
+      expect(changeSpy.calledAfter(validateSpy)).to.be.true;
+    });
+
+    it('should validate before change event on clear button click', () => {
+      comboBox.value = 'foo';
+      validateSpy.reset();
+      comboBox.inputElement.$.clearButton.click();
+      expect(validateSpy.calledOnce).to.be.true;
+      expect(changeSpy.calledOnce).to.be.true;
+      expect(changeSpy.calledAfter(validateSpy)).to.be.true;
     });
 
     it('should fire a validated event on validation success', () => {
@@ -82,15 +146,47 @@
       expect(event.detail.valid).to.be.false;
     });
   });
+
+  describe('required', () => {
+    let comboBox;
+
+    beforeEach(async() => {
+      comboBox = fixture('combo-box-required');
+      await nextRender();
+    });
+
+    it('should pass validation with value', () => {
+      comboBox.value = 'foo';
+      expect(comboBox.checkValidity()).to.be.true;
+    });
+
+    it('should fail validation without value', () => {
+      expect(comboBox.checkValidity()).to.be.false;
+    });
+  });
+
+  describe('required + value + invalid', () => {
+    let comboBox;
+
+    beforeEach(async() => {
+      comboBox = fixture('combo-box-required-value-invalid');
+      await nextRender();
+    });
+
+    it('should propagate invalid state to internal text-field', () => {
+      expect(comboBox.inputElement.invalid).to.be.true;
+    });
+  });
+
   describe('invalid cannot be set to false', () => {
     let comboBox;
-  
+
     beforeEach(async() => {
       comboBox = fixture('combo-box');
       comboBox._shouldSetInvalid = (invalid) => invalid;
       await nextRender();
     });
-  
+
     it('should set invalid only when it is true', async() => {
       comboBox.required = true;
       comboBox.validate();
