HIV-infected children represent an incredibly diverse group of patients, ranging from neonates to young adults. With the change in age and maturity, paediatric highly active antiretroviral therapy (HAART) evolves from the meticulous twice-daily dosing of ml of liquid preparations to a choice of once-daily dosing of a single fixed-dose coformulated tablet. The use of simplified paediatric regimens could enhance the ability to achieve successful implementation of HAART in HIV-infected children. Pharmacokinetics and pharmacodynamic studies of antiretroviral drugs and their combinations need to be conducted in infants, children and adolescents to develop appropriate dosing in each of these specific groups.