diff --git a/src/cdk/overlay/overlay-ref.ts b/src/cdk/overlay/overlay-ref.ts
index 5c6ddb1b5708..bfb0fbff1db1 100644
--- a/src/cdk/overlay/overlay-ref.ts
+++ b/src/cdk/overlay/overlay-ref.ts
@@ -273,14 +273,14 @@ export class OverlayRef implements PortalOutlet, OverlayReference {
   }
 
   /** Updates the position of the overlay based on the position strategy. */
-  updatePosition() {
+  updatePosition(): void {
     if (this._positionStrategy) {
       this._positionStrategy.apply();
     }
   }
 
   /** Switches to a new position strategy and updates the overlay position. */
-  updatePositionStrategy(strategy: PositionStrategy) {
+  updatePositionStrategy(strategy: PositionStrategy): void {
     if (strategy === this._positionStrategy) {
       return;
     }
@@ -298,17 +298,31 @@ export class OverlayRef implements PortalOutlet, OverlayReference {
   }
 
   /** Update the size properties of the overlay. */
-  updateSize(sizeConfig: OverlaySizeConfig) {
+  updateSize(sizeConfig: OverlaySizeConfig): void {
     this._config = {...this._config, ...sizeConfig};
     this._updateElementSize();
   }
 
   /** Sets the LTR/RTL direction for the overlay. */
-  setDirection(dir: Direction | Directionality) {
+  setDirection(dir: Direction | Directionality): void {
     this._config = {...this._config, direction: dir};
     this._updateElementDirection();
   }
 
+  /** Add a CSS class or an array of classes to the overlay pane. */
+  addPanelClass(classes: string | string[]): void {
+    if (this._pane) {
+      this._toggleClasses(this._pane, classes, true);
+    }
+  }
+
+  /** Remove a CSS class or an array of classes from the overlay pane. */
+  removePanelClass(classes: string | string[]): void {
+    if (this._pane) {
+      this._toggleClasses(this._pane, classes, false);
+    }
+  }
+
   /**
    * Returns the layout direction of the overlay panel.
    */
diff --git a/src/cdk/overlay/overlay.spec.ts b/src/cdk/overlay/overlay.spec.ts
index fc0555ddf7bd..f7da3fc088e7 100644
--- a/src/cdk/overlay/overlay.spec.ts
+++ b/src/cdk/overlay/overlay.spec.ts
@@ -398,6 +398,26 @@ describe('Overlay', () => {
     expect(overlayContainerElement.textContent).toBe('');
   });
 
+  it('should add and remove classes while open', () => {
+    let overlayRef = overlay.create();
+    overlayRef.attach(componentPortal);
+
+    const pane = overlayContainerElement.querySelector('.cdk-overlay-pane') as HTMLElement;
+    expect(pane.classList)
+      .not.toContain('custom-class-one', 'Expected class to be initially missing');
+
+    overlayRef.addPanelClass('custom-class-one');
+    expect(pane.classList).toContain('custom-class-one', 'Expected class to be added');
+
+    overlayRef.removePanelClass('custom-class-one');
+    expect(pane.classList).not.toContain('custom-class-one', 'Expected class to be removed');
+
+    // Destroy the overlay and make sure no errors are thrown when trying to alter
+    // panel classes
+    overlayRef.dispose();
+    expect(() => overlayRef.addPanelClass('custom-class-two')).not.toThrowError();
+  });
+
   describe('positioning', () => {
     let config: OverlayConfig;
 
diff --git a/src/dev-app/dialog/dialog-demo.html b/src/dev-app/dialog/dialog-demo.html
index ebf76c003267..7605af0d8911 100644
--- a/src/dev-app/dialog/dialog-demo.html
+++ b/src/dev-app/dialog/dialog-demo.html
@@ -123,5 +123,5 @@ <h2>Other options</h2>
 
   <p> {{ data.message }} </p>
   <button type="button" (click)="dialogRef.close(howMuch.value)">Close dialog</button>
-  <button (click)="dialogRef.updateSize('500px', '500px').updatePosition({ top: '25px', left: '25px' });">Change dimensions</button>`
+  <button (click)="dialogRef.updateSize('500px', '500px').updatePosition({top: '25px', left: '25px'});">Change dimensions</button>
 </ng-template>
diff --git a/src/dev-app/dialog/dialog-demo.ts b/src/dev-app/dialog/dialog-demo.ts
index b3640fa356be..d79a59931bdd 100644
--- a/src/dev-app/dialog/dialog-demo.ts
+++ b/src/dev-app/dialog/dialog-demo.ts
@@ -7,7 +7,7 @@
  */
 
 import {DOCUMENT} from '@angular/common';
-import {Component, Inject, TemplateRef, ViewChild} from '@angular/core';
+import {Component, Inject, TemplateRef, ViewChild, ViewEncapsulation} from '@angular/core';
 import {MAT_DIALOG_DATA, MatDialog, MatDialogConfig, MatDialogRef} from '@angular/material';
 
 
@@ -101,8 +101,11 @@ export class DialogDemo {
       <p cdkDragHandle> {{ data.message }} </p>
       <button type="button" (click)="dialogRef.close(howMuch.value)">Close dialog</button>
       <button (click)="togglePosition()">Change dimensions</button>
+      <button (click)="temporarilyHide()">Hide for 2 seconds</button>
     </div>
-  `
+  `,
+  encapsulation: ViewEncapsulation.None,
+  styles: [`.hidden-dialog { opacity: 0; }`]
 })
 export class JazzDialog {
   private _dimesionToggle = false;
@@ -124,6 +127,13 @@ export class JazzDialog {
         .updatePosition();
     }
   }
+
+  temporarilyHide(): void {
+    this.dialogRef.addPanelClass('hidden-dialog');
+    setTimeout(() => {
+      this.dialogRef.removePanelClass('hidden-dialog');
+    }, 2000);
+  }
 }
 
 
diff --git a/src/lib/dialog/dialog-ref.ts b/src/lib/dialog/dialog-ref.ts
index 98af86092b9e..490e5699480d 100644
--- a/src/lib/dialog/dialog-ref.ts
+++ b/src/lib/dialog/dialog-ref.ts
@@ -173,6 +173,18 @@ export class MatDialogRef<T, R = any> {
     return this;
   }
 
+  /** Add a CSS class or an array of classes to the overlay pane. */
+  addPanelClass(classes: string | string[]): this {
+    this._overlayRef.addPanelClass(classes);
+    return this;
+  }
+
+  /** Remove a CSS class or an array of classes from the overlay pane. */
+  removePanelClass(classes: string | string[]): this {
+    this._overlayRef.removePanelClass(classes);
+    return this;
+  }
+
   /**
    * Gets an observable that is notified when the dialog is finished opening.
    * @deprecated Use `afterOpened` instead.
diff --git a/src/lib/dialog/dialog.spec.ts b/src/lib/dialog/dialog.spec.ts
index d66934fa3b00..1195958d9fff 100644
--- a/src/lib/dialog/dialog.spec.ts
+++ b/src/lib/dialog/dialog.spec.ts
@@ -830,6 +830,23 @@ describe('MatDialog', () => {
     sibling.parentNode!.removeChild(sibling);
   }));
 
+  it('should add and remove classes while open', () => {
+    let dialogRef = dialog.open(PizzaMsg, {
+      disableClose: true,
+      viewContainerRef: testViewContainerRef
+    });
+
+    const pane = overlayContainerElement.querySelector('.cdk-overlay-pane') as HTMLElement;
+    expect(pane.classList)
+      .not.toContain('custom-class-one', 'Expected class to be initially missing');
+
+    dialogRef.addPanelClass('custom-class-one');
+    expect(pane.classList).toContain('custom-class-one', 'Expected class to be added');
+
+    dialogRef.removePanelClass('custom-class-one');
+    expect(pane.classList).not.toContain('custom-class-one', 'Expected class to be removed');
+  });
+
   describe('disableClose option', () => {
     it('should prevent closing via clicks on the backdrop', fakeAsync(() => {
       dialog.open(PizzaMsg, {
diff --git a/tools/public_api_guard/cdk/overlay.d.ts b/tools/public_api_guard/cdk/overlay.d.ts
index fc48e7f2f955..81c60a7a26aa 100644
--- a/tools/public_api_guard/cdk/overlay.d.ts
+++ b/tools/public_api_guard/cdk/overlay.d.ts
@@ -227,9 +227,10 @@ export declare class OverlayRef implements PortalOutlet, OverlayReference {
     readonly hostElement: HTMLElement;
     readonly overlayElement: HTMLElement;
     constructor(_portalOutlet: PortalOutlet, _host: HTMLElement, _pane: HTMLElement, _config: ImmutableObject<OverlayConfig>, _ngZone: NgZone, _keyboardDispatcher: OverlayKeyboardDispatcher, _document: Document, _location?: Location | undefined);
-    attach<T>(portal: TemplatePortal<T>): EmbeddedViewRef<T>;
+    addPanelClass(classes: string | string[]): void;
     attach(portal: any): any;
     attach<T>(portal: ComponentPortal<T>): ComponentRef<T>;
+    attach<T>(portal: TemplatePortal<T>): EmbeddedViewRef<T>;
     attachments(): Observable<void>;
     backdropClick(): Observable<MouseEvent>;
     detach(): any;
@@ -240,6 +241,7 @@ export declare class OverlayRef implements PortalOutlet, OverlayReference {
     getDirection(): Direction;
     hasAttached(): boolean;
     keydownEvents(): Observable<KeyboardEvent>;
+    removePanelClass(classes: string | string[]): void;
     setDirection(dir: Direction | Directionality): void;
     updatePosition(): void;
     updatePositionStrategy(strategy: PositionStrategy): void;