S4, E11: When one of J.D.'s (Zach Braff) favorite patients Harrison Marks (guest star John Bennett Perry) is in dire need of a kidney transplant, J.D. takes matters into his own hands by finding his long-lost son Murray (guest star Matthew Perry) in hopes that he'll donate his kidney. Despite Dr. Cox's (John C. McGinley) warning to J.D. not to interfere with family business, J.D. persists and complications arise. Meanwhile, Elliot (Sarah Chalke) is fed-up with co-workers not taking her seriously, and discovers she can get her way by flaunting her femininity with some help from Carla (Judy Reyes) and Jordan (guest star Christa Miller). Donald Faison, Neil Flynn and Ken Jenkins also star.