Stigmatization and discrimination of HIV/AIDS patients is an important issue specially in caring institutions. This would be minimized, among nurses who play a major role in these institutions, by improving AIDS knowledge and AIDS attitude. This study was conducted to assess the effectiveness of an AIDS education program on trainee nurses' AIDS knowledge and AIDS attitudes. Randomized controlled, pretest post-test study was carried out on students in National School of Nursing, Sri Lanka. All participants, experimental group (N = 65) and control group (N = 64), completed a self-administered instruments of HIV/AIDS knowledge scale and a AIDS attitudes scale at pre-test and post-test point. A focused AIDS education program was conducted for the experimental group. Differences in AIDS knowledge and attitudes, as evident by the differences in answers for pretest and post-test, in the two groups were compared. Data was analyzed using Statistical Package for the Social Sciences for WIN 18.0. Both AIDS knowledge (p < .001) and AIDS attitudes (p < .001) of the student nurses improved significantly after the intervention. Sub-dimensions of HIV/AIDS knowledge scale, namely HIV course and manifestations (t = -6.84, p < .001), HIV transmission (t = -7.28.44, p < .001), occupational risk of HIV and prevention (t = -10.59, p < .001) and management of HIV and anti-retroviral treatment (t = -12.81, p < .001) all showed significant improvement in the experimental group. Sub-dimensions of AIDS attitude scale, namely blame and judgment (t = -3.35, p = .001), attitudes towards imposed measures (t = -5.44, p < .001) and attitudes in comfortable in dealing with a HIV/AIDS patients (t = -4.25, p < .001) also showed significant improvement. This AIDS Education Program showed statistically significant improvement in the AIDS knowledge and AIDS attitudes of student nurses and its usefulness in reducing stigma and discrimination of People Living with HIV and its potential for future use in Sri Lanka and other countries with similar background.