Patrick Dempsey is handing in his scalpel in for some heavier machinery.
The Grey's Anatomy star, 44, told Brazilian reporters he has joined the cast of Transformers 3, according to website BOL Noticias. Dempsey said he will be playing a "dark" role in the film and is set to begin shooting this summer.
Transformers 3, starring Shia LaBeouf and directed by Michael Bay, is set to hit theaters July 1, 2011. Transformers: Revenge of the Fallen grossed more than $800 million worldwide.
Dempsey most recently was seen on the big screen in the ensemble comedy Valentine's Day.