Ulcerative colitis (UC) is a disease condition which typically affects young people; pregnancy is therefore frequent in women with this disease. 5-aminosalicylic acid (5-ASA) is known to be efficacious in maintaining remission of UC, but its safety in pregnancy has not yet been established. In the present study, the safety of 5-ASA was assessed in 16 women with UC (mean age: 31 years, range 25-35) who had a total of 19 pregnancies over the period from 1988 to 1992. All the patients were in clinical remission of UC at the beginning of pregnancy and were receiving a regular maintenance therapy with 5-ASA (ASACOL tablets, 1.2 g/day). During pregnancy, 4 women had a clinical relapse requiring treatment with higher doses of 5-ASA and, in some cases, with steroids. Our observations confirm that the treatment with 5-ASA does not affect the course of pregnancy nor does it damage the fetus, but it can protect from recurrences of UC.