Currently, there is no way to measure the effectiveness of cardiopulmonary resuscitation in humans. The literature suggests that minimum aortic diastolic and estimated coronary perfusion pressures during cardiopulmonary resuscitation (CPR) in the animal model correlate with higher resuscitation rates. Six patients were studied during CPR to determine the arterial diastolic and estimated coronary perfusion pressures (arterial minus right atrial diastolic pressures). Mean arterial pressures were 27/11 mm Hg, central venous pressures were 32/10 mm Hg, and the mean estimated coronary perfusion pressure was only 1 mm Hg. None of the six patients survived. This study demonstrates that the techniques of measuring hemodynamic values during CPR is practical. Poor estimated coronary perfusion pressures were obtained from the six patients studied. This study should be extended to include a large number of patients to determine whether these hemodynamic parameters can be used as prognostic indicators of successful resuscitation in humans.