In order to describe the incidence and the epidemiologic pattern of viral hepatitis (V.H.) in a French urban area, with a special attention to ambulatory cases, an epidemiological information system has been developed during one year. The physicians (sample), the medical laboratories and, at a lesser degree, the hospital care units, have taken part in this work. The incidence rate of ambulatory cares has been estimated 85 cases/10(5) persons (69/110), less than previously assumed. Non-B V.H. remains more frequent (52 cases/10(5) persons), but B.V.H. are rather close to them (33 cases/10(5) persons). Large differences exist between geographic areas, without evident rational. Higher incidence rates characterize children (especially 5-9 years) and migrant people (especially from North Africa): those facts are completely account by very high rates within the subgroup of migrant children (473 and 260 cases/10(5) persons). The reported patterns allows us to point on this high risk characteristic of migrant's children and to assume an important modification in the pattern of local inhabitants V.H. in the region. These trends have to be followed by further studies.