Thirty-nine asthmatic patients required mechanical ventilation (IPPV) for status asthamticus over a seven and a half year period. We reviewed their clinical records with particular emphasis on the events leading to intermittent positive pressure ventilation (IPPV) and the long-term courses of those patients who survived IPPV. Long delays by patients before seeking medical attention, incomplete assessment of acute attacks, underuse of corticosteroids prior to admission and overuse of sedation were important factors often influencing the necessity for IPPV. Four patients died during IPPV. Of the 35 who survived, 32 were regularly followed in our Respiratory Clinic. Nine patients subsequently died, eight undoubtedly from asthma. Serial measurements of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were retrospectively analyzed to determine patterns of asthma. Of the 23 patients still alive, 14 have well controlled asthma, five have a pattern of persistent airflow obstruction, two have markedly labile asthma, and two have gradually deteriorating airflow obstruction. By contrast, seven patients who died sufficiently long after IPPV to enable categorization of their patterns showed either markedly labile asthma or gradually deteriorating airflow obstruction. None had relatively constant ventilatory function at either normal or suboptimal levels. We suggest that patterns of asthma are useful guides in detecting patients at high-risk. Patterns characterized by markedly labile asthma or gradually deteriorating airflow obstruction appear to be associated with an increased risk of sudden death from asthma.