The outcome of mechanical ventilation is reported in a series of 43 patients managed in an intensive care unit in Sri Lanka. Eighteen patients (42%) survived. Of these, all except one were discharged from hospital. Patients with organophosphate poisoning and Guillain-Barré polyneuritis had a mortality of 47% and 50% respectively. Patients who were ventilated postoperatively as a result of anaesthetic complications during surgery had a mortality rate of 20%. Patients with tetanus and myasthenia gravis had 100% recovery. The following categories of patients had a poor prognosis with 100% mortality: patients with severe head injuries, subarachnoid haemorrhage, non-traumatic coma, severe chest injuries and porphyria. The series is compared to similar series from other countries.