Dimension X was an old-time radio program broadcast April 1950 to September 1951 on NBC.

Dimension X was the first notable adult science fiction series on radio, preceded only by the short-lived Two Thousand Plus , scattered episodes of anthology dramas, and juvenile fare, such as Flash Gordon.

The series featured adaptations of stories by respected science fiction writers such as Ray Bradbury, Isaac Asimov and Robert Heinlein. The first thirteen episodes were broadcast live, the remainder prerecorded.

Dimension X lasted only one year, but the later X Minus One utilized many of the same actors and scripts. All fifty episodes survive and are available from various retailers.