The case of a patient ulcerative colitis involving an autoimmune base who was treated with recombinant alpha-2 interferon for concomitantly presenting chronic hepatitis B in the replicative phase is reported. With this therapy unreplicative seroconversion of the disease was achieved without modification of the course of the chronic inflammatory intestinal disease (CIID) during treatment or over the posttreatment follow up period. A brief review of the literature was performed concerning the role of autoimmunity in ulcerative colitis, treatment with alpha-interferon in chronic hepatitis B and the exacerbation of autoimmune phenomena which may lead to interferon treatment. According to the evolution of this case and the review of the literature, the authors conclude that the existence of CIID does not contra-indicate the use of recombinant alpha-2 interferon in patients with chronic viral hepatitis, although special control of the disease should be carried out during the treatment period.