How many episodes were in season 5 of Lost?

17.

There were 17 episodes in the 5^th season of the hit ABC TV series ‘ËœLost’â„¢. The season premiered with a 2-hour broadcast on January 21, 2009. It ended on May 13, 2009 with a 2-episode season finale. The season proved to be the lowest-ranked for the series in terms of number of viewers, with only 9.428 million American viewers watching the season finale compared with 13.991 million for the preceding season (data from TV by the Numbers).