Clinical mentoring by providers skilled in HIV management has been identified as a cornerstone of scaling-up antiretroviral treatment in Africa, particularly in settings where expertise is limited. However, little data exist on its effectiveness and impact on improving the quality-of-care and clinical outcomes, especially for HIV-infected children. Since 2008, the Botswana-Baylor Children's Clinical Centre of Excellence (COE) has operated an outreach mentoring programme at clinical sites around Botswana. This study is a retrospective review of 374 paediatric charts at four outreach mentoring sites (Mochudi, Phutadikobo, Molepolole and Thamaga) evaluating the effectiveness of the programme as reflected in a number of clinically-relevant areas. Charts from one visit prior to initiation of mentoring and from one visit after approximately one year of mentoring were assessed for statistically-significant differences (p<0.05) in the documentation of clinically-relevant indicators. Mochudi showed notable improvements in all indicators analysed, with particular improvements in documentation of pill count, viral load (VL) results, correct laboratory monitoring and correct antiretroviral therapy (ART) dosing (p<0.0001, p<0.0001, p<0.0001 and p<0.0001, respectively). Broad and substantial improvements were also seen in Molepolole, with the most improvement in disclosure documentation of all four sites. At Thamaga, improvements were restricted to CD4 documentation (p<0.001), recent VL and documented pill count (p<0.05 and p<0.05, respectively). Phuthadikobo showed the least amount of improvement across indicators, with only VL documentation and correct ART dosing showing statistically-significant improvements (p<0.05 and p<0.0001, respectively). These findings suggest that clinical mentoring may assist improvements in a number of important areas, including ART dosing and monitoring; adherence assessment and assurance; and disclosure. Clinical mentoring may be a valuable tool in scale-up of quality paediatric HIV care-and-treatment outside specialised centres. Further study will help refine approaches to clinical mentoring, including assuring mentoring translates into improved clinical outcomes for HIV-infected children.