He doesn't. >.<
Sasuke hasn't really killed Naruto yet. But i think he will the last episode.
Sasuke apppears in the first episode
Sasuke has not died yet.
It was sealed into him in episode one. He first unleashed it in the episode where Haku nearly killed Sasuke. He first spoke to the Kyuubi during his training with Jiraiya before the chuunin finals.
Episode 109. an ep. or two later is when Sasuke retrieval arc. begins.
Sasuke joins Orochimaru in the end of episode 109 but everyone(except Sakura) finds out in episode 110
Itachi resurrected?... Yes Sasuke Killed?... No
Episode 117
episode 1001
Episode 211
Kabuto try to kill sasuke in "Naruto episode 51."