We performed a 12-month clinical trial to compare the relative effectiveness of an intermittent 5-ASA regimen and a continuous 5-ASA regimen for the maintenance treatment of patients with ulcerative colitis in remission. Fifty patients with ulcerative colitis in remission for a minimum period of 1 month participated in the study. Twenty five patients received an intermittent treatment with 5-ASA tablets (2.4 g for the first week of each month) and 25 received a continuous treatment with tablets (1.6 g each day). Patients were assessed clinically every two months and endoscopically every 6 months. Our results show that the two treatments were equally effective. The relapse-free rates at 12 months were 71% in patients receiving the intermittent treatment and 66% in patients given the continuous treatment. This difference is not statically significant. Further studies are needed to assess whether the intermittent regimen can be an alternative to life-long treatment in patients who have maintained remission for a long period of time.