Objective: To assess survival after cardiac arrest and to determine whether age is an independent determinant of late mortality or poor neurologic outcome. Design: Analyses using results of Brain Resuscitation Clinical Trial I (1979 to 1984) and Brain Resuscitation Clinical Trial II (1984 to 1989), two randomized, double-blind studies of outcome following cardiac arrest. Setting: A multicenter study in 12 acute care hospitals in nine countries (Brain Resuscitation Clinical Trial I), and 24 hospitals in eight countries (Brain Resuscitation Clinical Trial II). Patients: A total of 774 patients who were initially comatose after successful resuscitation from cardiac arrest. The analyses include both in- and out-of-hospital cardiac arrests. Results: The 6-month mortality rate for the entire group was 81%. Mortality rate was 94% for the oldest group (> 80 years) compared with 68% for the youngest group (≤ 45 years) (p > 0.01). Other independent predictors of mortality were history of diabetes mellitus, inhospital arrests, arrest time of > 5 min, history of congestive heart failure, a noncardiac cause of arrest, and cardiopulmonary resuscitation time of > 20 min. Of the 774 patients, 27% recovered good neurologic function. There was no statistically significant difference in neurologic recovery rates by age. Multivariate analysis showed that independent predictors of good neurologic recovery were: no history of diabetes mellitus, a cardiac cause of arrest, short arrest time, and short cardiopulmonary resuscitation time. Conclusion: Increasing age was a factor in postresuscitation mortality, but was not an independent predictor of poor neurologic outcome.