The intestinal helminth Oesophagostomum bifurcum is highly and focally endemic in northern Ghana and Togo, and its juveniles produce a nodular inflammatory response as they develop in the intestinal wall. This pathology can produce clinical symptoms. We report on 156 cases of oesophagostomiasis presenting in 1996-98 to Nalerigu hospital in northern Ghana. The disease accounted for 0.2% of the out-patient department new presentations (about 1 patient per week), and 1% (16) of the major acute surgical cases. Children aged 5-9 years were most commonly affected. Multinodular disease (13% of the cases) results from hundreds of pea-sized nodules within the colon wall and other intra-abdominal structures, and presents with general abdominal pain, persistent diarrhoea and weight loss. Dapaong tumour (87%) presents as an abdominal inflammatory mass often associated with fever. The 3-6-cm tumour is painful, well-delineated, smooth, spherical, 'wooden', periumbilical, and adhered to the abdominal wall. Cases most commonly presented during the late rains and early dry season. Diagnosis by ultrasound has reduced the need for exploratory surgery, and the ability to sonographically evaluate conservative treatment with albendazole has curtailed management by colectomy or incision and drainage.