The objective of this study was to present some epidemiological characteristics of persons tested for HIV/AIDS at the Voluntary Counselling and Testing Centre (VCT) Zagreb that was founded in November 2004. The majority of clients tested were between 25 and 29 years old and had a secondary level education. 78% of the clients tested reported one risky behaviour in the past, the majority of which was attributed to risky heterosexual behaviour (having unprotected sexual intercourse). 35% of the clients reported having never or only occasionally used condom with a non-regular partner. 30% of the clients with a history of injecting drug use reported that they never "shared" injecting equipment. The results presented in this paper could be a useful tool for public health officers when targeting interventions for HIV prevention.