Hitherto, services have failed to deliver the UK Government's 1988 recommendation to vaccinate injecting drug users (IDUs) against hepatitis B virus (HBV). In April 1999, the Scottish Prison Service implemented an initiative to offer HBV vaccination to all inmates; we sought to determine the impact of this initiative on the IDU population. Among community-recruited IDUs (who had injected for < or =5 years) in Glasgow, vaccine uptake was significantly higher among those surveyed in 2001-2002 (52% of 387) than in 1993 (16% of 166), 1994 (19% of 138) or January-March 1999 (15% of 128); of the 2001-2002 vaccinees, 56% had been vaccinated in prison. Our results indicate that the universal offer of vaccination to all prisoners, within two years of the initiative's implementation, has had a dramatic impact on uptake among IDUs.