[en] We report a heterosexual patient with HIV infection and a CD4 T-cell count of 0.45 x 10(9)/L who developed mild ulcerative proctitis, sacroileitis and oligoarthiritis. While he was treated with 5-aminosalicylic enemas, the patient rapidly developed severe pancolitis. An emergency colectomy without procetectomy was performed. A few months later, he suffered recurrence of ulcerative proctitis, aggravation of arthritic pain and developed anterior uveitis. All symptoms disappeared after proctectomy. There was no evidence for opportunistic infection or Kaposi's sarcoma. Antineutrophil cytoplasmic antibodies were positive and the HLA-B27 antigen was present. CD4 counts were lower during the phases of active disease than during remission. This case demonstrates that severe ulcerative colitis can occur in the presence of moderate T-cell defects. In view of a recent report of remission of Crohn's disease under comparable circumstances, it is possible that the extent of T-cell involvement in both diseases is radically different.