Ultrasonography has already revealed that up to 50% of individuals in some villages in northern Ghana have colonic pathology induced by Oesophagostomum bifurcum. Approximately 2% of those affected progress to clinical oesophagostomiasis if left untreated. In the present study, ultrasound-positive children living in a heavily infected community were each given 5 days of treatment with albendazole (10 mg/kg.day), early in the dry season. Treatment reduced the prevalence, number, size and half-life of the ultrasound-visible nodules, stopped the excretion of O. bifurcum eggs, and reduced the development of clinical oesophagostomiasis during the subsequent 8 months. However, the treatment had no impact on the new infections that occurred during the following rainy season, and no impact on nodule prevalence by the end of that rainy season. Surgical management may not be essential in non-acute cases of clinical oesophagostomiasis, as albendazole may kill the nodule-dwelling worms.