The patients are followed for 36 months and monitored each six months through viral load in plasma using ExaVir Load®, CD4+ T-cell count, adherence, clinical examination including physical development. Viral load will be assessed using a new ELISA based technique ExaVir Load® that detects HIV reverse transcriptase down to 1 fg/ml blood-plasma corresponding to 200 HIV RNA copies/ml. Adherence will be assessed every three months using questionnaires designed specifically for age groups. For infants and young children the Pediatric International Adherence Questionnaire (PIAQ) may be used, and for older children the Adult AIDS Clinical Trials Group (ACTG) Adherence Instruments will be used. The questionnaire interviews will be conducted by health personnel at the Out Patient Clinics for Pediatric HIV. Adherence will also be measured by pill count, where the patients bring their remaining drugs back to the clinic at follow-up, enabling calculation of the proportion of drugs remaining out of the total amount of prescribed drugs as well as through pharmacy records if the patients have collected the drugs accurately. Assessment of side effects will be done according to WHO suggested monitoring and management of ARV drugs together with the clinical examination each three months.