Between 1954 and 1988 only a total of twenty five cases of primary adenocarcinoma of the small bowel (excluding periampillary tumours) were recorded at the Department of Histopathology, Belfast City Hospital. Of these, 14 tumours were located in the jejunum: the remainder arose in the ileum. The average age at presentation was 61.3 years and a slight female to male preponderance of 1:7:1 was noted. The adenocarcinoma arose from a preexisting villous adenoma in six cases. The overall prognosis was poor, with a five year survival of 15.7%. All the survivors had tumours located in the jejunum. The single most important prognostic indicator was the depth of tumour invasion or stage at the time of diagnosis. Tumour size and grade did not seem to correlate well with survival. It is concluded that the rarity of these tumours and their inaccessibility hinder detection and treatment and that surgical resection is more effective than chemotherapy.