Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Are at least 18 years old.
• Agree not to have intercourse 2 weeks before, during, and 2 weeks after study or agree to use effective methods of birth control.
• Have had HIV-1 RNA levels less than 400 copies/ml on the 2 most recent measurements.
• Have at least 1 of the following situations:
• (a) at least 1 of the following: (1) decrease in facial fat, (2) decrease in fat in lower limbs, or (3) decrease in fat in buttocks area; or
• (b) an increase in lactate level greater than 2.2 mmol/L at the screening visit plus at least 1 of the following: (1) decrease in facial fat, (2) decrease in fat in lower limbs, or (3) decrease in fat in the buttocks area; or
• (c) an increase in lactate level greater than 2.2 mmol/L at screening visit plus at least 2 of the following: (1) shortness of breath, (2) weakness, (3) fast heartbeat, (4) recent weight loss (10 lbs. within the past 2 months), (5) pain and/or bloating in the abdomen, (6) nausea and/or vomiting and/or lack of appetite; or
• (d) lactate level greater than 3.2 mmol/L at the screening visit.
• Are able to read at a sixth-grade level.
• Have taken d4T consistently for the 6 months before entering study.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have diabetes or kidney failure.
• Have any condition that makes them unable to participate in this study.
• Are unable to take medications by mouth.
• Have serious medical conditions, such as congestive heart failure or other heart disease, which would affect the safety of the patient.
• Are taking or have taken abacavir plus Retrovir or Combivir.
• Are pregnant or breast-feeding.
• Are enrolled in other clinical studies.
• Have had a reaction to or are unable to take abacavir and have taken Retrovir in the past.
• Have taken hydroxyurea within the past 3 days or plan to take this drug during the study.
• Have had chemotherapy or radiation therapy within 4 weeks prior to screening visit (except for local treatment for Kaposi's sarcoma) or plan to have such treatment during the study.
• Have taken drugs that affect the immune system, such as systemic corticosteroids, interleukins, vaccines, or interferons, within 4 weeks prior to the screening visit.
• Have had an HIV vaccine within 3 months of the screening visit.
• Have taken recombinant Human Growth Hormone (r-hGH), megestrol acetate, medicines containing oxandrolone, oxymetholone, nandrolone, DHEA, or other testosterone derivatives, or glucocorticoids or other systemic steroids (except inhaled and topical steroids) in the last 4 months or plan to take these drugs during the study.