On June 3, 1965, a Titan II rocket launched this spacecraft, Gemini IV, carrying astronauts James McDivitt and Edward White into orbit. The flight lasted four days and included a historic space walk by White, the first by an American, early in the mission. Ten weeks earlier, Soviet cosmonaut Alexei Leonov had become the first human to "walk in space." NASA broadcast the audio from White's 22-minute "extra-vehicular activity" (EVA) live; he enormously enjoyed the experience.

The flight plan also included a rendezvous with the discarded second stage of the Titan II rocket. It was aborted, however, after pilot Jim McDivitt experienced unexpected difficulties reaching the booster because he had not been properly trained in rendezvous techniques. Other experiments during this flight included Earth photography, space radiation measurements, and medical effects of prolonged weightlessness. In 1967 NASA transferred the spacecraft to the Smithsonian.