A prospective study was conducted on 344 children aged from 3 months to 16 years with acute appendicitis. Most children presented with typical features of acute appendicitis (70%) or peritonitis (28%). Atypical presentation was uncommon and occurred only in seven young children, masquerading as intestinal obstruction, gastroenteritis or urinary tract infection. Prolonged delay in surgery was associated with a rise in incidence of late appendicitis (gangrenous and perforated appendicitis). This rise was especially marked 37 h after onset of symptoms. The main causes of delay were inability of the parents and primary care medical practitioners to recognize the disease early. Surgeons contributed very little to the delay. High risk factors for postappendectomy sepsis were young children under 6 years old, late appendicitis, obese patients, inferior systemic antibiotic regimes and inexperienced surgeons. Young children had high postoperative sepsis mainly because of the high incidence of late appendicitis due to their inability to express their symptoms properly. They were not especially prone to postappendectomy sepsis; they had the same degree of appendicitis compared with older children. Measures to decrease the postappendectomy morbidity are suggested.