There exists great variability in the literature as to the percentage of cases of sudden and unexpected infant death in which definable causes can be identified. Review was undertaken of the clinical and family histories, death scene features including parental interviews, and pathological and microbiological features of 361 consecutive cases presenting as sudden and unexpected infant death with minimal preceding symptoms and signs to the Adelaide Children's Hospital over a 10-year period from 1983 to 1992. Three hundred and twenty-nine cases of SIDS were identified. Nine cases (2.5%) were attributed to accidental asphyxia based partly on death scene examination. This left only 23 cases (6.4%), which were due to a variety of other diverse entities including sepsis, volvulus with sepsis, congenital cardiac disease, probable metabolic disorders, heat stroke, and unclassifiable disorders. This relatively low figure lends support to definitions of SIDS that emphasize the importance of death scene investigation and clinical history review prior to postmortem examination.