This review (under the International Joint Learning Initiative on Children and AIDS) provides a detailed evidence analysis of gender, children and AIDS. Six systematic reviews provide the most up to date evidence base on research surrounding children and HIV on key topics of treatment resistance and adherence, schooling, nutrition, cognitive development and orphaning and bereavement. Traditional systematic review techniques were used to identify all published studies on four key topics, then studies were selected according to adequacy criteria (sufficient size, control group and adequate measures). A gender analysis was performed on included studies, detailing whether gender was measured, results were analysed by gender or any gender-based findings. For family studies, both the gender of the parents and gender of the child are needed. Secondary analysis by gender was performed on existing systematic reviews for treatment resistance and adherence. Of the 12 studies on treatment resistance, 11 did not look at gender. One found boys at a seven-fold risk compared to girls. For medication adherence, gender was not significant. Of the 15 studies on schooling, 12 analysed findings by gender with an overall female disadvantage. Of the 14 studies on nutrition, nine analysed by gender with mixed findings. Of the 54 studies on cognitive development, 17 provided gender data, but only four analysed by gender with few differences established. Of the 15 studies on bereavement, seven analysed data by gender again with mixed findings. Major policies fail to provide gender data for young children. WHO, UNAIDS and the international data sets are not gathered or coded by gender for young children (generally under 15 years of age) despite well-established gender challenges in later life. This review shows that the current evidence base is inadequate. Data on gender variation and outcome are urgently needed to inform policy and research on children and HIV.