diff --git a/packages/mdc-textfield/adapter.js b/packages/mdc-textfield/adapter.js
index 6f9b4c25d53..64438d00f86 100644
--- a/packages/mdc-textfield/adapter.js
+++ b/packages/mdc-textfield/adapter.js
@@ -129,14 +129,6 @@ class MDCTextFieldAdapter {
    */
   getNativeInput() {}
 
-  /**
-   * Returns the idle outline element's computed style value of the given css property `propertyName`.
-   * We achieve this via `getComputedStyle(...).getPropertyValue(propertyName)`.
-   * @param {string} propertyName
-   * @return {string}
-   */
-  getIdleOutlineStyleValue(propertyName) {}
-
   /**
    * Returns true if the textfield is focused.
    * We achieve this via `document.activeElement === this.root_`.