Inclusion Criteria

Children may be eligible for this study if they:

• Are at least 3 months old and no older than 17 years of age. This is the age the child needs to be at the time they begin the study.
• Are HIV positive.
• Weigh more than 5.5 pounds. A newborn child must have reached at least 38 weeks of gestation.
• Have or have not taken anti-HIV drugs. Those that have not must have a viral load between 5,000 and 500,000 copies/ml at screening. Those that have must have been taking anti-HIV drugs, including lamivudine, for at least 3 months and have a viral load of no more than 400 copies/ml at screening.
• Have a CD4 count of more than 200 cells/mm3.
• Have written consent from parent or guardian.
• Are willing to use effective birth control during the study and for 1 month after the last dose of emtricitabine, if sexually active.

Exclusion Criteria

Children will not be eligible for this study if they:

• Are pregnant or breast-feeding.
• Cannot follow the visit or dosing schedule or are not available for 1 year.
• Have taken experimental drugs or vaccines (except for emivirine and experimental forms of approved drugs) within 30 days of study start.
• Have nerve damage in their arms or legs.
• Have trouble eating or taking drugs.
• Have serious diarrhea within 30 days before study entry.
• Have had any serious illness within 30 days of study screening. Any treatment must have been finished 14 days before study entry.
• Have had an AIDS-related (opportunistic) disease within 12 months of screening.
• Are being treated for tuberculosis.
• Have had pancreatitis.
• Require certain drugs.