We retrospectively investigated the annual incidence and prevalence of inflammatory bowel disease (IBD) from 1981 to 1988 in an urban and a rural area of central Spain. Two hundred and eighty-one patients presented with IBD; 193 ulcerative colitis (UC) and 88 Crohn's disease (CD) (prevalence 43.4/100,000 and 19.8/100,000, respectively). Of these patients, 168 were diagnosed for the first time during the study period. One hundred and eleven UC and 57 CD (incidence 3.16/100,000 and 1.61/100,000 respectively). Within the urban area, the UC incidence was 3.15/100,000 and the CD 1.87/100,000. In the rural area, the incidence for the UC was 3.25/100,000 and 0.86/100,000 for the CD. No sex differences were found. The incidence rates have increased significantly (p < 0.05) for CD in the study period. However, for UC rates did not change. During 1986-1988, the patient's age at the time of diagnosis was significantly lower than that of 1981-1983 (p < 0.05).