Forty-one intra-abdominal abscesses in 30 Nigerian children seen over a 2-year period at the Obafemi Awolowo University Teaching Hospital were studied prospectively to determine their location, aetiology, microbiology and clinical course. Thirty-four abscesses (83%) were intraperitoneal with the subphrenic spaces and pelvis being the commonly involved intraperitoneal sites. Six abscesses (15%) were retroperitoneal while there was only one visceral abscess (2%). Diseases of the gastrointestinal tract occurring in 20 patients (67%) were responsible for the majority of intraperitoneal abscesses, while suppurating external iliac adenitis was the major cause of retroperitoneal abscesses. There were 62 microbiological isolates, with 52% being anaerobic bacteria and 47% aerobic bacteria. A fungus, Candida, was isolated once (2%). Escherichia coli and Staphylococcus aureus were the commonest aerobic bacteria, while Bacteroides and anaerobic streptococci were the commonest anaerobes. Sixteen patients (53%) had a mixed flora of aerobic and anaerobic bacteria, while in seven patients each (23%) only aerobic or anaerobic bacteria were isolated. The mortality rate in this series was 23%. Association of an intra-abdominal abscess with remote organ failure, postoperative anastomotic leakage, non-localization of the abscess within the peritoneal cavity and gastrointestinal perforation due to typhoid enteritis was found to portend poor prognosis.