While the show initially enjoyed high ratings, the average rating of the show at the end of its first season dropped to 52nd out of 94 programs. Unhappy with the show's ratings, NBC threatened to cancel the show during its second season. The show's fan base, led by Bjo Trimble, conducted an unprecedented letter-writing campaign, petitioning the network to keep the show on the air. NBC renewed the show, but moved it from primetime to the "Friday night death slot", and substantially reduced its budget. In protest Roddenberry resigned as producer and reduced his direct involvement in Star Trek, which led to Fred Freiberger becoming producer for the show's third and final season. Despite another letter-writing campaign, NBC cancelled the series after three seasons and 79 episodes.

Answer this question: how many episodes of star trek in total? Let's think fast. Stream of consciousness:
This is the relevant information: Despite another letter-writing campaign, NBC cancelled the series after three seasons and 79 episodes. So the final answer is 79.