Background: HIV-1 vertically infected children stand a high risk of HIV-1 drug resistance (HIVDR), especially after failure to prevention of mother to child transmission (PMTCT) and pediatric antiretroviral therapy (ART). Thus, surveillance of HIVDR might contribute in delineating optimal pediatric regimens. Objective: To evaluate HIVDR and subtype distribution among ART-naïve and ART-failing children. Methods: A study was conducted throughout 2017 amongst 102 children/adolescents at the “Chantal BIYA International Reference Centre” (CIRCB) in Cameroon. HIVDR testing was performed in protease-reverse transcriptase (RT) region and interpreted using the Stanford HIVdbv8.5; subtyping was performed using MEGA v7.0.26; and data were analysed using Epi-info v7.1.3.3, with p<0.05 considered statistically significant. Results: Sequences were generated from 63 participants (19 ART-naïve, 44 ART-failure); the median-age was respectively 6[IQR:3.5–11] and 144[IQR:116.25–185] months for ART-naïve and ART-failing (median ART-duration: 23.55 [IQR:7.61–60.91] months, 63.6% receiving non-nucleoside RT inhibitors [NNRTI]-based regimens). Among ART-naïve children, overall-HIVDR was 52.6%(10/19), with 31.6%(6/19) to NNRTI, 26.3%(5/19) to NRTI and 15.8%(3/19) to PI/r. Among ART-failing children, overall-HIVDR was 97.7%(43/44), with 95.4%(42/44) to NNRTI, 90.9%(40/44) to NRTI and 18.2%(8/44) to PI/r. Multi-drug resistance was found in 21.05%(4/19) ART-naïve versus 85.7%(24/28) on NNRTI-based and 50%(8/16) on PI-based regimens; OR=4.36, p=0.045. CRF02_AG was prevalent (68.2%), without any effect on HIVDR (p=0.99). Conclusion: The high rates of HIVDR, in both ART-naïve and ART-failing children, suggest using GRT for selecting optimal pediatric ART-regimens. Multi-drug resistance is concerning among children failing ART and prompts the need of new drugs (integrase inhibitors, darunavir/ritonavir) for optimal pediatric ART management.