During a 10 year period. 20 dogs with primary localized neoplasia of the small intestine were presented at the University of Bristol Veterinary School. Half the tumours were carcinomas, the remainder being lymphosarcomas (5 cases), leiomyosarcomas (3 cases) and leiomyomas (2 cases) Lesions occurred at a variety of locations along the tract, but descending duodenum (6 cases) and terminal ileum (4 cases) were the commonest sites. Clinical findings varied. All dogs except three presented with chronic illnesses, but only seven showed signs immediately referable to alimentary tract disease. Abnormalities were found at radiographic examination in all cases except one and provided or confirmed the indication for laparotomy. Ten animals were destroyed at the time of surgery, two died during the immediate post-operative period and three were later destroyed because of suspected recurrence. Four dogs are reported well at intervals of between nine months and two years following surgery.