Background - The aim of this retrospective study was to determine the cumulative incidence of adhesive small bowel obstruction (SBO) after total or subtotal colectomy and to investigate the site of the obstructive adhesions in the abdominal cavity. Methods - The records of 234 patients who underwent colectomy from 1985 to 1994 were reviewed for SBO, potential risk factors for SBO, and the site of adhesions causing obstruction. Mean follow-up, which was complete in 215 patients, was 63 months. Results - SBO occurred in 56 patients (24 per cent) of whom 42 (18 per cent) had adhesive obstruction. The risk of SBO due to adhesions within 1 year was 11 per cent, increasing to 30 per cent 10 years after colectomy. With univariate analysis no risk factor for adhesive SBO, including previous laparotomies, septic complications and omental resection, was identified. The most common site of obstructing adhesions was the pelvis (ten of 28 patients). Conclusion - The incidence of SBO after colectomy is high. Colectomy may be a suitable model for studies of adhesion prevention.