39 missionaries working at 38 separate mission hospitals or clinics in Bangladesh. India, Nepal and Pakistan completed questionnaires about their clinical practice during the previous year, 1980. Data were collected about gastrointestinal disorders, including coeliac disease, tropical sprue, bloody diarrhoea, amoebiasis, typhoid, cholera, inflammatory bowel disease and diverticular disease. More than 386,000 out-patients and over 56,000 in-patients were treated with an estimated 12,272 cases of bloody diarrhoea, 7,310 of amoebiasis, 2,113 of typhoid and 872 cases of intestinal tuberculosis, 74 cases of inflammatory bowel disease were diagnosed, of which 56 were ulcerative colitis and the remainder were said to have Crohn's disease. Surgery was performed in 28 hospitals, but only 10 (26%) had a histology service. Inflammatory bowel disease appears to be a relatively more common cause of diarrhoea in the Indian subcontinent than in sub-Saharan Africa (z = 5.47, p less than 0.001). The proportion of patients with bloody diarrhoea who have ulcerative colitis Crohn's disease was similar throughout the region. The rate of cases having ulcerative colitis rather than Crohn's disease was greater in India (z = 3.1, p less than 0.005), and in Bangladesh (z = 3.2, p less than 0.005), than in Pakistan (z = 1.28, NS) or Nepal and Bhutan (z = 0, NS). The relative risk of Indians developing ulcerative colitis rather than Crohn's disease is 2.6 (95% confidence limits 1.4-4.8, NS). This may reflect diagnostic difficulties in distinguishing Crohn's disease from intestinal tuberculosis, but it may also shed light on similar differences now being reported in migrant groups in Western Europe.