The high rate of transmission of blood borne viral infections (BBVI) (such as hepatitis C, hepatitis B and HIV/AIDS) among injecting drug users (IDUs), and the seriousness of the resulting diseases, means that IDUs are commonly tested for BBVI, particularly if they attend drug treatment clinics. The assumption appears to be that if IDUs know their serostatus they are in a better position to protect both themselves and their communities by behaviour change and improved health care. Yet the HIV testing literature suggests that this assumption is oversimplified, and there is little or no contemporary literature that examines the human factors involved in being tested for hepatitis C or B, or being vaccinated against hepatitis B. Australian IDU research has indicated that IDUs being tested for all three viruses experience difficulties with all aspects of being tested. These difficulties include motivations for being tested that do not include willingness to change behaviour; the intimidatory nature of the testing process that deters some (particularly young) IDUs from presenting for testing, or from collecting test results; failure to understand the meaning of test result which may result from inadequate pre-and post-test counselling; over-testing; and uncertainty about serostatus and hepatitis B vaccination process or status. This study has been funded by the National Health and Medical Research Council to investigate the human factors involved in testing IDUs for hepatitis C, hepatitis B and/or HIV and vaccination against hepatitis B. IDUs recruited from drug treatment, youth, sexual health and needle exchange agencies, will be interviewed about the behavioural, cognitive and affective aspects of the decision to be tested, the test process and test outcomes, and similar issues relating to vaccination against hepatitis B. Service providers across the country will also be interviewed. The study should elucidate areas of confusion, anxiety or difficulties in testing that can arise, so that testing and referral agencies and health professionals can improve test practices, including, but not exclusively, pre- and post-testing counselling.