Sixty patients with active distal ulcerative colitis participated in a multicentre randomized double-blind trial to compare the effect of a beclomethasone dipropionate (BDP) enema (3 mg/100 ml) with 5-aminosalicylic acid (5-ASA) enemas (2 g/ 100 ml) and enemas with a combination of BDP/5-ASA (3 mg/2 g/100 ml). The patients were treated for 4 weeks and the efficacy of the drugs was evaluated by sigmoidoscopy, histology and subjective symptoms after that time. The overall results after 28 days of treatment were: clinical improvement 100% (BDP/5-ASA) vs. 70% (BDP) and 76% (5-ASA); endoscopic improvement 100% (BDP/5-ASA) vs. 75% (BDP) and 71% (5-ASA); histological improvement 95% (BDP/5-ASA) vs. 50% (BDP) and 48% (5-ASA). After 4 weeks of treatment seven of 19 patients (37%) receiving BDP/5-ASA had healed endoscopically, compared with six of 20 receiving BDP (30%) and two of 21 receiving 5-ASA (10%). Two patients on 5-ASA and three on BDP had a marked deterioration during treatment. The combination of BDP and 5-ASA was significantly superior to single-agent therapy in terms of both improved sigmoidoscopic and improved histological score. No differences in improvement between the 5-ASA vs. BDP-treated patients were noticed. No side effects were seen. The results of the study show that topical treatment of active distal ulcerative colitis with either 5-ASA or BDP is equally efficacious. So far, no data on topical combination therapy have been described. However, combination therapy with BDP/5-ASA seems superior to single-agent therapy and causes no adverse reactions.