A case of adult hypertrophic pyloric stenosis presented in an older female with no apparent predisposing factors which might be likely to precipitate the condition. There was a history of chronic dyspepsia and occasional episodes of vomiting. No contributory medical history was identified. Barium swallow and follow through showed a markedly reduced emptying time of the stomach. A partial gastrectomy was eventually done and on histopathological examination a diagnosis of adult hypertrophic pyloric stenosis was made.