The effect of a single dose of suxamethonium on cardiac rate and rhythm during halothane anesthesia with barbiturate induction was studied in a prospective, triple‐blind trial with 28 patients. No atropine was given and patients were not intubated. A slight but significant preponderance of sinus‐bradycardia without hemodynamic consequrnces was found in the group given suxamethonium. Suxametlionium did not provoke ventricular ectopies or conduction disturbanccs. It is concluded that in anesthesia with barbiturate induction, but without atropine or intubation, the use of a single dose of suxamethonium is a safe procrdure with regard to cardiac rate and rhythm.