BACKGROUND: Two doses of live-attenuated varicella-zoster vaccine are recommended for human immunodeficiency virus 1 (HIV-1)-infected children with CD4% >/=15%. We determined the prevalence and persistence of antibody in immunized children with perinatal HIV (PHIV) and their association with number of vaccinations, combination antiretroviral therapy (cART), and HIV status. METHODS: The Adolescent Master Protocol is an observational study of children with PHIV and perinatally HIV-exposed but uninfected (PHEU) children conducted at 15 US sites. In a cross-sectional analysis, we tested participants' most recent stored sera for varicella antibody using whole-cell and glycoprotein enzyme-linked immunosorbent assay. Seropositivity predictors were identified using multivariable logistic regression models and C statistics. RESULTS: Samples were available for 432 children with PHIV and 221 PHEU children; 82% of children with PHIV and 97% of PHEU children were seropositive (P < .001). Seropositivity after 1 vaccine dose among children with PHIV and PHEU children was 100% at <3 years (both), 73% and 100% at 3-<7 years (P < .05), and 77% and 97% at >/=7 years (P < .01), respectively. Seropositivity among recipients of 2 vaccine doses was >94% at all intervals. Independent predictors of seropositivity among children with PHIV were receipt of 2 vaccine doses, receipt of 1 dose while on >/=3 months of cART, compared with none (adjusted odds ratio [aOR]: 14.0 and 2.8, respectively; P < .001 for overall dose effect), and in those vaccinated >/=3 years previously, duration of cART (aOR: 1.29 per year increase, P = .02). CONCLUSIONS: Humoral immune responses to varicella vaccine are best achieved when children with PHIV receive their first dose >/=3 months after cART initiation and maintained by completion of the 2-dose series and long-term cART use.