Jennifer Esposito is the only cast member to have left "Blue Bloods" through its five-year run ending in 2015. While on the show she played the character Detective First Grade Jackie Curatola in 46 episodes.
Esposito appeared in the sixth episode of the first season and remained on the show until episode 51 in the third season. Her character was written off the show in Season 3, Episode 7. The on-screen reason given is that Detective Curatola needed time off due to stress, so she took an official leave of absence. Off-screen, the actress was medically suspended from the show due to her need to cut back on working hours as a result of her Celiac disease. CBS, the television network that airs "Blue Bloods," suspendd Esposito from the show without pay, but kept her on contract. As part of her contract terms she cannot take another network job or appear in a show airing in the same time slot.
There have been multiple cast members who have increased their parts from small recurring roles to starring roles. These cast members includes Amy Carlson, Sami Gayle, Marissa Ramirez and Vanessa Ray. Both Carlson and Gayle have been with the show since the first season, while Ramirez joined the show in its third season and Gayle in its fourth.