This is an open-label (all people know the identity of the intervention), study to evaluate the pharmacokinetics, safety and antiviral activity. Approximately 24 HIV-1 infected children will be enrolled in this study. The study consists of a 4-week screening period, a 48-week treatment period, and a 4-week follow-up period. Participants will receive DRV/rtv according to their body weight. Safety evaluations will include assessment of adverse events, laboratory tests, physical Examination, neurologic examination, vital signs, and electrocardiogram. The total duration of the study will be 56 weeks.