Few if any prearrest or intraarrest variables have been identified as highly predictive of inhospital mortality following cardiopulmonary arrest. A total of 310 consecutive patients requiring advanced cardiac life support during the calendar years 1985 and 1986 were reviewed with respect to eight specific variables. These included age, diagnosis, location, mechanism of the event, duration of resuscitation, whether the event was witnessed or unwitnessed, the initial observed rhythm and medications administered. A total of 37.1 percent of the patients were successfully resuscitated, but only 9.7 percent survived until discharge. Factors strongly associated with inhospital mortality included unwitnessed events (p = 0.0316), the need for epinephrine (p = 0.0003), identification of electromechanical dissociation or asystole as initial rhythms (p = 0.0000), and cardiac vs respiratory mechanism of arrest (p = 0.0000).