The incidence of primary sclerosing cholangitis has been estimated on the basis of its frequent association with ulcerative colitis, but direct epidemiologic studies have not yet been carried out. In the current study we report a survey of clinical and epidemiological aspects of primary sclerosing cholangitis in Spain. A questionnaire was circulated to physicians in 33 hospitals throughout Spain to ascertain the number and the clinical, biochemical and immunologic characteristics of patients with primary sclerosing cholangitis from January 1, 1984 to December 31, 1988. Twenty-three centers, from 12 Spanish regions, covering a population of 19.23 million answered the questionnaire. Forty-three patients (60.5% males) with a mean age of 42.3 years (range 12 to 75 years) were seen during the 5-year period. At presentation, 16% of the cases were asymptomatic. Ulcerative colitis was present in 44.2% of cases, and one patient had Crohn's disease. The overall annual incidence ranged from 0.16 to 0.68 cases/million from 1985 to 1988, and the annual prevalence increased from 0.78 cases/million in 1984 to 2.24 cases/million in 1988. No geographical differences were found, but there was a trend to detect more cases in industrialized regions. In conclusion, there was a continuing rise in the annual incidence and prevalence of primary sclerosing cholangitis in Spain over a 5-year period.