In four Southern African countries where the HIV prevalence rate is among the highest in the world, 46.4% of a sample of female adolescents infected with HIV report having never engaged in sex. This would indicate either the dominance of non-sexual modes of HIV transmission or rampant misreporting of sexual behavior in the sample. We propose a method to estimate the extent of misreporting and calculate that the true percentages of virgins among the sample of HIV-infected adolescent women is 32.1%. After accounting for misreporting, the contribution of sexual modes of HIV transmission is projected as 50.4%, compared with an estimate of 35.5% if we assume no misreporting. Copyright © 2013 John Wiley & Sons, Ltd.