Finland has, until recently, had a very low incidence of hepatitis B infection, reflected in transmission mainly amongst adolescent and adult age-groups with high-risk behaviour. Several recent local outbreaks of acute hepatitis B in Finland may indicate a change in the epidemiology of this infection. We examine time trends of hepatitis B notifications to the new national infectious disease registry. We also analyse all hepatitis B cases notified over the 2-y period from 1 January 1995 to 31 December 1997 by age, sex, place of residence, country of birth and reported route of transmission. The reported incidence of acute hepatitis B increased 3-fold over this period. The main reported route of transmission was related to injecting drug use, although a significant proportion of adolescent female cases was reportedly infected through heterosexual intercourse. A critical evaluation of the current targeted vaccination approach and other prevention policies is required.