Thirty five children died of acute appendicitis in England and Wales in 1980-4 compared with 204 in 1963-7. Thirteen of the 35 deaths in 1980-4 took place at home or on the day of admission to hospital before operation and a further 18 on the day of operation or the first day after it. Thirty one of the children had peritonitis. A third of the deaths were in children aged 0-4 years, and the hospital fatality rate in this age group was one death in 320 cases compared with one death in 4760 cases in children aged 5-14 years. The fall in the number of deaths between the 1960s and the 1980s was due to improvements in medical care, a reduction in the incidence of appendicitis, and changes in the age structure of the child population. Difficulty and delay in diagnosis and inadequate intravenous therapy are now the main factors contributing to death.