Mercury-Atlas 3 (MA-3) was launched unmanned on April 25, 1961 at 16:15 UTC, from Launch Complex 14 at Cape Canaveral, Florida. The Mercury capsule contained a robotic "mechanical astronaut". Mercury spacecraft No. 8 and Atlas No. 8 100-D were used in the mission.

The mission was terminated by the range safety officer after 43.3 seconds due to failure of the launch vehicle to follow its roll and pitch programs. Although the launch vehicle was destroyed, considerable benefit was derived from the flight test. The launch escape system saved the Mercury spacecraft from destruction. The capsule flew to an apogee of 7.2 km and downrange only 1.8 km.

The flight of the Mercury capsule lasted 7 minutes and 19 seconds, most of that time descending on its parachute. The spacecraft was recovered some 20 minutes after launch in the Atlantic Ocean and reused on the next flight (MA-4) as spacecraft No. 8A.