PURPOSE:The aim of this study was to compare the efficacy of intermittent therapy with mesalazine enemas and continuous oral mesalazine to maintain remission of distal ulcerative colitis or proctitis.METHODS:Thirt‐yeight patients with distal ulcerative colitis (n=17) or ulcerative proctitis (n=21) in clinical, endoscopic, and histologic remission were randomly assigned to receive either oral mesalazine (0.5 g three times/day, Eudragit L coating, n=19) or intermittent therapy with mesalazine enemas (4 g of 5‐aminosalicylic acid enema every third night, n=19). Both groups were comparable in regard to sex, age, age at disease onset, extent and duration of disease, number and mode of treatment of previous attacks, and time in remission. Patients were reviewed at the beginning of the study and, subsequently, at two‐month intervals for 24 months or until a relapse occurred. At each visit, diaries were reviewed and clinical and laboratory assessments were performed. Sigmoidoscopy was carried out and biopsies were obtained by a blinded observer. Histology was assessed without knowledge of the patient's clinical state or treatment category.RESULTS:At the end of the study, 6 of 19 patients on oral mesalazine (32 percent) and 14 of 19 patients on mesalazine enemas (74 percent) were still in full remission (log rank test: 15.280,P<0.001). Differences in relapse rates between groups were significant even when data were stratified by extent of disease(P<0.01). In the oral group, six and seven patients relapsed at 12 and 24 months, respectively. In the enema group, three and two relapses occurred in the first and second year of the study, respectively. All patients complied with the treatment satisfactorily and there were no dropouts.CONCLUSION:These results suggest that intermittent therapy with mesalazine enemas is more effective than continuous oral mesalazine in maintaining remission in patients with distal ulcerative colitis and proctitis.