In the episode "Old Times", while a patient at Northwestern, he was visited by his mentor and good friend Dr. Peter Benton, to whom he revealed that his marriage with Kem was going through a rough patch. In the same episode, Dr. Benton acted as a back-seat driver and supervised the operation to make sure Carter was well taken care of. Thanks to Benton's thoroughness which initially annoyed the surgeon performing the operation, a complication was resolved and the operation was a success. Unbeknownst to Carter, the kidney was arranged for him thanks to the efforts of his old friends Carol Hathaway and Doug Ross who were also unaware that they were helping Carter and only found out that "some doctor" got the kidney.