Small bowel obstruction (SBO) as a late complication of the treatment of Hodgkin's disease was found in 32 of 398 (8%) patients followed over a 20 year period. The vast majority of these patients had an initial staging laparotomy as part of staging protocols. Of 51 obstructive episodes, 13 were diagnosed clinically, 12 of the 13 had prior radiological or surgical documentation. Thirty-one episodes were shown radiologically; four were demonstrated at laparotomy and three recurrent episodes were identified in an unspecified manner. The median duration of each episode was 3 days and the median time between commencement from treatment for Hodgkin's disease and the development of a SBO was 21 months. Thirty-one of the 32 patients had had a staging laparotomy or prior abdominal surgery. Two patients had SBO because of non-Hodgkin's lymphoma and one had SBO secondary to short bowel syndrome. These are thus not true complications of disease treatment. Twenty-nine of the 32 or 7.2% of patients thus had possible treatment-related SBO. The cause of SBO was recorded as adhesions from previous surgery in 27 of the 51 episodes. This was confirmed at laparotomy in 16 patients. Twenty-five of the 32 patients had received abdominal irradiation but only three obstructive episodes were attributed to radiation enteritis and fibrosis. In one of 22 patients who received chemotherapy, Vinblastine was implicated as a cause for SBO. Eighteen patients required laparotomy to lyse adhesions while the others were treated conservatively with tube drainage.(ABSTRACT TRUNCATED AT 250 WORDS)