Carcinosarcoma and sarcomatoid carcinoma of the bladder after organ transplantation is higher in comparison to the general population but overall occurrence is still very uncommon. Due to the decreased immunitary response effects of antirejection drugs, these cancers have aggressive course and respond poorly to treatment. Bladder drained pancreatic transplants are associated with a number of urologic challenges that can delay the diagnosis and the treatment of malignancies of the genito-urinary system. The authors present a case of a rare sarcomatoid carcinoma of the bladder following bladder drained simultaneous kidney and pancreas transplant and discuss its pathogenesis and clinical management.