"Good Luck, Ruth Johnson" is the ninth episode of the fifth season of ER. The episode was the series' 100th episode. It first aired in December 10, 1998 on NBC. It was written by Lydia Woodward and directed by Rod Holcomb. It has John Carter giving someone name Ruth Johnson a tour of the hospital since she was born in the same hospital 100 years ago while Carol Hathaway learns a terrifying truth behind a fatal shooting of a boy's friend.