HIV/AIDS is a global issue and the fourth biggest killer worldwide. Report from Ministry Of Health Malaysia showed factory workers are among the social group that are mostly infected (10.4%). A cross~sectional study was carried out to determine the socio-demographic factor and its relationship with knowledge, attitude and HIV-related risk behavior among factory workers in Selangor, Negeri Sembilan and MaIacca. This study involved 3300 factory workers selected randomly and were given self-guided questionnaire. With response rate about 95.4% (3148), the level of knowledge was high (97.3%) and the attitude was positive (81 %). However there was still an amount of fear towards HIV/AlDS patient. Logistic regression showed significant difference (p<0.05) between level of knowledge and ethnic group, income and level of education and between attitude and income and level of knowledge. About 27.7% of respondents smoked cigarette. 4.2% involved with drugs of which 0.7% administered intravenously, 2.3% were homosexuals, 2.5% were bisexuals and 3.1% were hererosexuals. HIV/AIDS prevention and control intervention should take into consideration the local socio-cultural factors and commitment from the top level management in the factory·