A 81-year-old patient developed a TUR-syndrome gradually one and half an hour after termination of TURP. Surgery was complicated by perforation of the bladder dome at the end of TURP. Due to extravasation of the perioperative irrigating fluid intraperitoneally and intravascular resorption a TUR-syndrome became apparent. Early diagnosis and rapid initiation of appropriate intensive care resulted in a benign postoperative course and the patient attained full recovery.