Chlorhydrate nefopam was used in the prophylaxis and treatment of postoperative shivering in 54 patients undergoing general anesthesia for radical cystectomy with trans-intestinal anastomosis. Postoperative shivering was not observed in any of the patients treated with nefopam before coming round, whereas it occurred in 55% of patients treated with placebo. Chlorhydrate nefopam subsequently stopped shivering in all these patients. The main side effects observed took the form of delayed awakening in 11% of patients receiving prophylactic treatment and somnolence lasting 5-10 minutes in all other patients.