The unmanned Saturn/Apollo 5 was the first test flight of the Lunar Module. Mission objectives were to verify the ascent and descent stages, the propulsion systems and the restart operations, and to evaluate the spacecraft structure, Lunar Module staging, second stage (S-IVB) and instrument unit orbital performance.

After launch, the S-IVB second stage ignited to insert the spacecraft into a 163 x 222-kilometer (101 x 137.9-mile) Earth orbit with a period of 88.3 minutes and an inclination of 31.63 degrees. The nose cone was jettisoned, and after a coast of 43 minutes and 52 seconds the Lunar Module was separated from the Lunar Module adapter. The Lunar Module entered a 167 x 222-kilometer (103.7 x 137.9-mile) orbit with a period of 88.4 minutes and an inclination of 31.63 degrees. A planned descent propulsion system burn of 39 seconds was cut short after only 4 seconds.

An alternate flight plan was put into effect, in which the descent propulsion system fired for 26 seconds at 10 percent thrust and then for 7 seconds at maximum thrust. A third descent propulsion system firing was performed 32 seconds later, consisting of a 26-second burn at 10 percent thrust and 2 seconds at maximum thrust, followed by a burn to simulate an abort during the landing phase, in which the ascent propulsion system, or APS, was ignited simultaneously with the descent propulsion system being shut down. The ascent propulsion system burn lasted 60 seconds, followed by a 6 minute, 23 second firing, which depleted ascent propulsion system fuel.

At the end of the 11 hour, 10 minute test period, both Lunar Module stages were left in orbit eventually to reenter and disintegrate. Despite the initial premature descent propulsion system shutdown, the mission was deemed a success and operation of all Lunar Module systems was confirmed.