Factors contributing to India’s vulnerability to the AIDS epidemic include pervasive poverty, low levels of education and high gender stratification. This study uses data collected in the 1998–99 National Family Health Survey-2 (NFHS-2) to investigate the relationship between aspects of women’s autonomy and four measures of HIV-related knowledge and behaviour – awareness and knowledge of HIV/AIDS, condom awareness and condom use – in three culturally contrasting states in India: Kerala (n=2884), Karnataka (n=4357) and Uttar Pradesh (n=8981). The NFHS-2 is a nationally representative survey of India, with a sampling scheme that was designed such that each state sample can be generalized back to represent ever-married women aged 15–49 living in the state. Kerala scores highest in the four health outcome measures, followed by Karnataka and then Uttar Pradesh, but condom use is lowest in Karnataka. Kerala also leads in the four dimensions of autonomy examined and in socio-demographic status, followed again by Karnataka and Uttar Pradesh. Despite these observed differences, in all three states, women with greater autonomy as measured by this study were more likely to be knowledgeable about AIDS and condoms and to use condoms, after controlling for socio-demographic factors. These results concur with other studies focusing on women’s autonomy and health outcomes around the world, and point to the importance of incorporating a gender-based approach to AIDS prevention programmes in India.