The thirty-first series of the British medical drama television series Casualty commenced airing on BBC One in the United Kingdom on 27 August 2016, and concluded on 29 July 2017. The series consisted of 44 episodes, including the show's feature-length thirtieth anniversary special episode, "Too Old for This Shift". Erika Hossington continued her role as series producer, while Oliver Kent continued his role as the show's executive producer until the end of the series. Seventeen cast members reprised their roles from the previous series with original character Lisa "Duffy" Duffin returning to the series as part of the show's thirtieth anniversary. Rik Makarem appeared in the series between October 2016 and January 2017 as first year foundation doctor (F1) Sebastian Grayling. This series also featured the death of regular character Caleb Knight, who has appeared since series 28.

"Too Old for This Shift" is a special feature-length episode of the British medical drama television series Casualty. It was broadcast as the premiere episode of its thirty-first series on 27 August 2016, on BBC One, to commemorate the 30th anniversary of the show. The special, which is 99 minutes long, was co-written by Matthew Barry and Andy Bayliss, directed by Steve Hughes, and produced by Lucy Raffety.