To ascertain the anaesthetic complications requiring post-anaesthetic respiratory support in a large obstetrical hospital, the hospital records of obstetrical patients admitted to an adjacent general intensive care unit (ICU) were studied. Obstetrical patients who required mechanical ventilation following anaesthetic complications were identified and their hospital records reviewed. In a ten-year period there were 61,435 women delivered at the Mater Mothers Hospital (MMH) in Brisbane, Queensland, Australia. Of these 24,161 had an anaesthetic associated with delivery including 7,452 general anaesthetics (GAs) and 16,709 regional anaesthetics (RAs). There were also 3,708 GAs and 17 RAs for procedures other than delivery. During this period there were 126 obstetrical admissions to the ICU. Sixteen were due to anaesthetic complications, twelve followed GA and four followed RA. Complications included anaphylaxis, high block and failure of tracheal intubation. The incidence of a major complication of a GA causing admission to the ICU was 1 in 932 and for RA was 1 in 4177 when these were given for delivery (P less than 0.01). If a complication requiring ICU admission and mechanical ventilation is used as the criterion of safety it appears that RA is safer than a GA for delivery.