This article reports three patients with acute leukaemia who presented with acute abdomen as the first manifestation of the disease. Leukaemic infiltrates of the bowel and appendix may have caused the abdominal symptoms in these patients. Acute leukaemia should be included in the differential diagnosis of severe abdominal pain associated with an abnormal blood count. This report highlights the importance of early diagnosis of acute leukaemia as initiation of cytotoxic chemotherapy results in prompt resolution of the abdominal catastrophe and obviates the need for surgery.