Background: The success of antiretroviral therapy (ART) depends on a high level of adherence to a life-long regimen of antiretroviral drugs (ARVs). Adherence is a concern in children because of factors relating to children such as age, disclosure status of HIV sero- status, and understanding of the medication. Few studies have determined the level of adherence of ART among children since the scale-up of access to ARVs in the study areas. This study was thus undertaken to determine the level of ART adherence among pediatric pat ients at an ART clinic, the reasons for non-adherence, and the factors associated with adherence, according to mothers/caregivers' reports.