Treatment of HIV with highly active antiretroviral therapy (HAART) has resulted in declining morbidity and mortality rates from HIV-associated diseases, but concerns regarding access and adherence are growing. To determine the adherence level and the reasons for non-adhering to antiretroviral therapy (ART) among children attending the clinic for infectious diseases at Aminu Kano Teaching Hospital in Nigeria, a cross-sectional study using the selfreport tool was carried out among 40 children with HIV infection who had been on ART for at least six months. Thirty-two patients (80%) were 95% or more adherent to their medications. The most common reasons for nonadherence were running out of medicines and the inability to purchase more due to financial constraints; other barriers were non-availability and inaccessibility to medications. Eighty-five percent of the paediatric patients took their medications at the same time everyday, and scheduled appointments were kept by 87.5%. The social class of the patients did not significantly affect adherence level. The level of adherence to ART was comparable to levels reported from other developing and developed countries. The cost of ART, and availability and accessibility to medications were the most significant barriers to adherence. Expanded access to subsidised antiretroviral drugs should improve adherence - and consequently treatment outcomes - for patients receiving this treatment in resource-poor settings.