Repetitive precordial thumping is the simplest method of temporary cardiac pacing. In 90 patients out of 100 with witnessed cardiac arrest because of asystole or marked bradycardia the critical situation could be effectively bridged over by this until a sufficient spontaneous rhythm returned or electrostimulation was ready to function. 69 patients were conscious during the stimulation. During the mechanical pacing only in 2 patients there occurred ventricular flutter or fibrillation, which was stopped by electric defibrillation. The existence of the myocardial contractility is the presupposition for effective mechanical and electrical pacing.