Patients with inflammatory bowel disease diagnosed in the greater Cape Town area between the years 1980 and 1984 inclusive were studied to establish the incidence and presenting features of these diseases. Case details were obtained from the records of the Groote Schuur Hospital group and Tygerberg Hospital as well as from questionnaires completed by 97% of 731 medical practitioners in the area. There were 134 patients with Crohn's disease, 197 with ulcerative colitis and 16 with indeterminate colitis. The incidences of Crohn's disease in the coloured, white and black population groups were calculated to be 1.8, 2.6 and 0.3/100 000 per year respectively and those for ulcerative colitis 1.9, 5.0 and 0.6/100 000 respectively. Among Jews the incidence was higher for both Crohn's disease (10.4/100 000) and ulcerative colitis (17.0/100 000). Of patients with ulcerative colitis 35% had limited proctitis, 26% proctosigmoiditis, 12% left-sided disease and 27% total colitis. Of patients with Crohn's disease 27% had colonic involvement alone, 37% ileocolitis and 36% small-bowel involvement alone. The incidence of inflammatory bowel disease has increased in the greater Cape Town area over the last 10 years, while the pattern of disease has remained similar to that previously reported for this geographical area.