In Italy, although the most recent guidelines stress the importance of screening for the human immunodeficiency virus (HIV) and the hepatitis B and C viruses (HBV and HCV) those subjects considered to be at high risk (e.g., injecting drug users), not all drug users being treated at public drug dependency centres are regularly tested for these infections. The results of the present study show that 7.2%, 13.0%, and 7.4% of injecting drug users seeking treatment at public drug dependency centres are not tested for, respectively, HIV, HBV and HCV infections and while corresponding figures for drug users who do not inject drugs are 20.3%, 25.1% and 16.2%. The failure to undergo testing among injectors was associated with a shorter history of drug use and with drug centres in central or southern Italy; these associations were also found among non-injectors, with the addition of low level of education. The results stress the importance of facilitating access to testing, of providing the drug dependency centres with the necessary resources for taking blood samples at the centres themselves, of making access to (and performance of) testing uniform throughout the country, and of removing obstacles that can lead to the drug user's refusal to undergo testing.