BACKGROUND: The UNAIDS 90-90-90 strategy clearly stipulates that 90% of all people on antiretroviral therapy (ART) should have a suppressed viral load. Intensified adherence counselling (IAC) was recently recommended by WHO to improve viral suppression among ART-treated paediatric and adolescent clients with virological failure. This paper describes the implementation and outcomes of IAC in the first year of implementation in a public ART program, to inform strategic interventions to reach the "third 90" among children. METHODS: A retrospective chart review was conducted for all children aged 9 months to 19 years with HIV viral loads (VL) ≥ 1000 copies/ml at 15 public health facilities from June 2015-December 2016. Data on initial VL test results, IAC sessions, repeat VL test results, and ART regimen switch were abstracted and analysed for completion of IAC and viral suppression after IAC. RESULTS: A total of 449 children had a detectable viral load above 1000 copies/ml, after an average of 3.5 years (SD 5.8) years of ART. 192 (43%) were 10-20 years of age, and 320 (71%) were receiving Nevirapine-based ART regimen. Out of 345 (77%) who completed the recommended three IAC sessions, 62 (23%) achieved viral suppression following IAC. The mean time from 1st to 3rd IAC session was 113 (SD 153) days and 172 (50%) of the children had completed the three sessions within 200 days. CONCLUSION: Suppression rates were low among ART-treated children with virological failure that completed the recommended three IAC sessions. As we move towards having 90% of ART-treated children and adolescents achieve and maintain viral suppression, there is need to re-evaluate the implementation of IAC among children and adolescents to consider both psychosocial and biological factors such as resistance testing for those with multiple detectable viral loads.