The present paper describes the development and evaluation of an intervention programme aiming to reduce adolescents' discriminatory attitudes toward people living with HIV/AIDS (PLWHA). The intervention programme integrates components of 'virtual interaction' with PLWHA (watching a documentary), knowledge enhancement and a simple cognitive exercise. To evaluate its effectiveness, the programme was implemented to about 600 form 3-4 (grade 9-10) students of three secondary schools in Hong Kong. Using a structured questionnaire, the level of discriminatory attitudes toward PLWHA, knowledge about HIV/AIDS and perceptions about PLWHA, etc. were measured before and after the implementation of the programme. A notable improvement on the level of acceptance of PLWHA and knowledge about HIV/AIDS was found after the implementation of the programme. Negative perceptions about PLWHA also reduced substantially. For instance, before the programme, over one-third (35.7%) of all respondents believed that the majority of PLWHA were promiscuous; the figure dropped to 15.8% after exposure to the programme (adjusted odds ratio = 0.35, p < 0.001). Further, some gender differences were observed. Female respondents tended to be less discriminatory toward PLWHA and responded more favourably to the programme than their male counterparts.