Characterized by Rhimes as a dork with issues expressing her feelings, Lexie's focal storyline in the series involved her romantic relationship with plastics attending Mark Sloan (Eric Dane). Both she and Mark sustained life-threatening injuries during an aviation accident in the eighth-season finale, which resulted in their deaths. Seattle Grace Mercy West is later renamed Grey-Sloan Memorial Hospital in their memory. The reason given for Lexie's departure after five years on the show was Leigh's desire to spend more time with her family.

Based on this passage, when does lexie grey die in grey's anatomy? Let's think fast. Stream of consciousness:
The relevant sentence in the passage is: Both she and Mark sustained life-threatening injuries during an aviation accident in the eighth-season finale, which resulted in their deaths. So the final answer is the eighth - season finale.