This study compared the effectiveness of an AIDS knowledge-only program (knowledge) with a combined program of AIDS knowledge and contact with people having HIV/AIDS (PHA) (knowledge-contact) in reducing nursing students' stigma and discrimination towards PHA and in enhancing their emotional competence to serve PHA. Eighty-nine nursing students from two universities in Hong Kong were randomly assigned to either the knowledge or the knowledge-contact condition. All participants completed measures of AIDS knowledge, stigmatizing attitudes, fear of contagion, willingness to treat, positive affect, and negative affect at pre-test, post-test, and six-week follow-up. Findings showed that in both groups, significant improvement in AIDS knowledge, stigmatizing attitudes, fear of contagion, willingness to treat, and negative affect were found at post-test. The effects on AIDS knowledge, fear of contagion, willingness to treat, and negative affect were sustained at follow-up for both groups. Intergroup comparisons at post-test showed that the effectiveness of knowledge-contact program was significantly greater than knowledge program in improving stigmatizing attitudes. No significant difference between the two groups was found at follow-up. Findings showed the short-term effect of contact in improving nursing students' attitudes and emotional competence in serving PHA. Implications for research and training of nursing staff were discussed. (C) 2010 Elsevier Ltd. All rights reserved.