STUDY DESIGN: Survival following mechanical ventilation for acute respiratory failure has important implications for medical decision-making and allocation of expensive resources for critical care. PROCEDURE: We reviewed a 5-year experience with mechanical ventilation in 383 men with acute respiratory failure and studied the impact of patient age, cause of acute respiratory failure, and duration of mechanical ventilation on survival. Survival rates were 66.6 percent to weaning, 61.1 percent to ICU discharge, 49.6 percent to hospital discharge, and 30.1 percent to 1 year after hospital discharge. When our data were combined with 10 previously reported series, mean survival rates were calculated to be 62 percent to ventilator weaning, 46 percent to ICU discharge, 43 percent to hospital discharge, and 30 percent to 1 year after discharge. Of 255 patients weaned from mechanical ventilation, 44 (17.3 percent) required an additional period of mechanical ventilation during the same hospitalization. RESULTS: Age had a significant influence on survival to hospital discharge and on that to 1 year after hospital discharge, and the cause of acute respiratory failure had a significant influence on survival only to weaning. Survival was best in younger patients and those with COPD or postoperative respiratory failure and worst in patients resuscitated after cardiac or respiratory arrest. Increased duration of mechanical ventilation significantly reduced survival only to hospital discharge. Overall survival was significantly affected by age and cause of acute respiratory failure, but not by duration of mechanical ventilation. CONCLUSION: We conclude that age, cause of acute respiratory failure, and duration of mechanical ventilation have specific influences on the generally poor outcome of mechanical ventilation for acute respiratory failure.