A prospective study of a Finnish population of about 250,000 patients with jaundice or unjaundiced cholestasis was carried out. During a two-and-a-half year period altogether 343 patients entered the study. The male/female ratio was 46%/54%. The mean age was 64.9 years (range 19-92). Extrahepatic obstructive diseases constituted two-thirds of the cases both in the jaundiced and unjaundiced cholestatic patient groups. The leading extrahepatic diseases causing jaundice were gallstone disease (61%) and pancreatic carcinoma (19%). Among the nonobstructive intrahepatic diseases causing jaundice, the most frequent diseases were alcoholic liver disease (32%) and viral hepatitis (21%). In patients with unjaundiced cholestasis, the spectrum of diseases resembled that of the jaundiced patients, gallstone disease and pancreatic carcinoma being the largest disease groups. In conclusion, extrahepatic obstructive processes seem to be the major aetiology of jaundice and unjaundiced cholestasis in our study population.