The present study examined the prevalence of and factors associated with deferrable risk behaviours practised by male voluntary blood donors in Hong Kong. Attitudes aud knowledge related to HIV/AIDS and blood donation among both male and female blood donors were also studied. In total, 2,162 (1,190 male and 972 female) blood donors in four Hong Kong Red Cross Blood Transfusion Services (HKRCBTS) centres completed an anonymous structured questiomaire. About 11% of the male respondents have practised deferrable risk behaviours (e.g. sharing syringes, cotizmercial sex-lzetworking, or having sex with another man). Furthermore, among male respondents, 5.9% indicated that they are using blood donatiotts as a means of testing for their HIVstatus. These male ‘potential test seekers’ tended to be younger, single, ummployed and first-time donors; relevant knowledge and perceptions towards the screeiziizggrideliize were also associated with potetttial test seeking and deferrable risk. About 5% of all respondents would go to the HKRCBTS to perfoniz an HIV test, if required. Many blood doizors in H012g Kong were not knowledgeable about HIV-related issues. There is a need to review the effectiveness of the present deferral system, which is based on the goodwill of the donor to disclose personal health risk factors.