Results STUDY POPULATION, COMPLIANCE, AND ESTIMATION OF BIAS IN PATIENT ACCESSION During the two years of the study, of the 10 151 people who were contacted, 6917 were enrolled (compliance 69%). Those citizens who did not respond to the first invitation were reinvited by letter or by telephone call, but the percentage of accession of this group was low (15%). As previously reported, overall compliance was higher in women than in men (73 v 66%; difference not significant Young people, especially those aged showed lower compliance than older people (65% v 77% difference not significant) The results reported in this paper are based on 6534 subjects--that is, the entire original cohort (n 6917), from which anti-HCV and HBSAg positive subjects (n 314) were removed. Seventy subjects who either failed to get their blood tests or complete the question naire were removed. In order to identify possible bias, reviewed epidemiological data from 1991 on the entire population of the two provinces con- taining the Dionysos Study towns (about with million people) and compared them demographic characteristics of the cohort nrolled. As described more fully elsewhere the ratio of men to women, wine i year per person), and prevalence of gallstones our study group and the broader population