A cross-sectional study to determine the prevalence of Human Immunodeficiency Virus (HIV) and HIV associated risk behavior was conducted in February 1998 among 6,324 drug users in 26 drug rehabilitation centres in Malaysia. The majority of respondents were males (97.3%) and Malays (77.8%), administered drugs intravenously (64.6%) and of these 65.4% shared needles. About 78.1% had sexual exposure, of which 55.1% had sex with girl friends, 31.3% with prostitutes and 4.6% with male partners. The HIV prevalence rate in the group was 12.1% and significantly high among injecting drug users (IDU); those sharing needles; those who started addiction at a young age (10-15 years); those who had sexual exposures and had sex with prostitutes.