[영문]The study compared the level of discriminatory attitudes toward people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) (PLWHA) and people with mental illness (PMI) and investigated factors associated with the absolute and relative levels of these discriminatory attitudes. An anonymous cross-sectional telephone survey interviewed 604 Chinese adults aged 18-50 years from the general Hong Kong population. Discriminatory attitudes toward both groups are prevalent, and with that toward PLWHA stronger than that toward PMI. Over half (58%) would rather make social contact with PMI than with PLWHA. Among other factors, respondents who perceived PLWHA to be promiscuous or perceived PLWHA to cause apprehensiveness in others had a higher likelihood of being more discriminatory toward PLWHA than toward PMI. These respondents were also more willing to make social contact with PMI than with PLWHA. Factors such as those related to less sympathy or unfavorable perceptions toward PLWHA were associated with discriminatory attitudes toward both PLWHA and PMI. Discriminatory attitudes toward the two groups were positively correlated with one another (r = 0.58, P qqqlt; 0.001). PLWHA face stronger discriminatory attitudes than PMI. Value-laden judgment and less frequent opportunities for personal interaction with PLWHA may partially explain the differences. Discriminatory attitudes toward different social groups may share similar underlying roots.