We examine the effects of HIV-infection on school attendance in Zimbabwe using recent nationally representative data of 11,673 children aged 6-18 years. We employ a non-linear multivariate decomposition approach to examine how HIV affects gender gaps in school attendance. We find gaps in school attendance between HIV-positive boys and girls and between HIV-negative and positive girls. About 44% of the attendance gap in both cohorts is attributed to differences in observable characteristics. About 56% of this gap is attributed to differences in the effects of these characteristics. The results indicate that HIV mainly affects girls' school attendance.