Inclusion Criteria:

Patients will be included when they meet the following criteria:

1. 18 years of age or older.
2. Ability and willingness to provide signed and dated written informed consent prior to admission to the study in accordance with GCP and local legislation.
3. Patients on stable therapy with Trizivir only (or its equivalent component drugs), for at least 6 months prior to screening.
4. Patients with plasma HIV-1-RNA <=50 copies/mL documented on at least two occasions within 6 months prior to enrollment.
5. Documentation of plasma HIV-1 RNA of <=50 copies/mL for >=6 months while on Trizivir without other antiretroviral agent. Documentation will include dates and results of all viral load testing from the previous six months.
6. Ability and willingness to complete the study.

Exclusion Criteria:

Patients will not be included when they meet one or more of the following criteria:

1. Previous exposure to NNRTI drugs.
2. Documented diabetes mellitus.
3. Documented hypertension (systolic >155 mmHg and/or diastolic >95 mmHg).
4. Fasting hypertriglyceridemia (>5.6 mmol/L or 500 mg/dl).
5. Use of lipid-lowering medication during the 90 days prior to study enrollment.
6. Chronic active hepatitis B and/or C infection by history.
7. Anemia (Hb <7.0 mmol/l or 11 g/dl hematocrit <32%).
8. Active opportunistic infection or neoplasm within 3 months prior to screening visit with the exception of cutaneous Kaposi's sarcoma without evidence of progressive disease.
9. Any history of cardiovascular disease (infarction, heart failure, peripheral vascular disease, cerebrovascular disease).
10. Hepatic, renal or thyroid abnormalities, as determined significant by the Principal Investigator.
11. Pregnancy or lactation.
12. Active anticoagulation therapy (coumarin derivates, heparin).
13. History of HIV-2 infection.
14. Female patients with CD4 counts >250 cells/mm3.
15. Male patients with CD4 counts >400 cells/mm3. Others which can not be listed here.