The purpose of this study is to determine whether raltegravir 400 mg b.i.d. in a boosted PI regimen is as efficacious and safe as the NRTI backbone in a boosted PI regimen.

Inclusion Criteria:

1. Patient is a male or female at least 18 years of age on the day of signing the informed consent.

2. Patient is HIV positive as determined by enzyme-linked immunosorbent assay (ELISA) or HIV PCR.

3. Patient has documented HIV RNA <75 copies/mL for at least 3 months prior to study entry while on a stable boosted PI based regimen without a change in antiretroviral therapy and with no documentation of HIV RNA > or = 75 copies/mL during this time.

4. Patient has no history of documented coronary artery disease that clinical investigator deems as clinically significant.

5. Patient has the following laboratory values within 35 days prior to the treatment phase of this study:

   • Alkaline phosphatase ≤ 5.0 x upper limit of normal
   • AST (SGOT) and ALT (SGPT) ≤ 5.0 x upper limit of normal. Patients with Hepatitis C Coinfection may be enrolled provided the patients are stable and meet all eligibility criteria.

6. Patient has no clinical evidence of active pulmonary disease; at the investigators, discretion a chest x-ray could be obtained if felt necessary.

7. Patient who is of reproductive potential agrees to use an acceptable method of birth control throughout the study.

8. Patient agrees to remain off prohibited concomitant medications as outlined in Section 3.2.1 of the protocol.

Exclusion Criteria:

1. Patients who are currently failing a boosted PI based regimen.
2. Patient is receiving a second line boosted PI regimen including boosted tripranavir or boosted darunavir.
3. Patients with chronic hepatitis B infection.
4. Patient has a history or current evidence of any condition, therapy, laboratory abnormality or other circumstance that might confound the results of the study, or interfere with the patient's participation for the full duration of the study, such that it is not in the best interest of the patient to participate.
5. Patient has a history of alcohol or other substance abuse that in the opinion of the investigator would interfere with patient compliance or safety.
6. Patient is currently participating or has participated in a study with an investigational compound or device within 30 days of signing informed consent.
7. Patient has ever used any experimental HIV-integrase inhibitor.
8. Patient has used systemic immunosuppressive therapy (e.g., 20 mg or more of prednisone or equivalent per day) within one month prior to treatment in this study. Short courses of corticosteroids (e.g., as for asthma exacerbation) will be allowed.
9. Patient requires hemodialysis.
10. Patient has significant hypersensitivity or other contraindication to any of the components of the study drugs.
11. Patient has chronic hepatitis, including chronic hepatitis B and/or C and has decompensated liver disease.
12. Patient is pregnant or breastfeeding, or expecting to conceive (within the duration of the study). Patient is expecting to donate eggs (within the duration of the study). Patient is expecting to donate sperm (within the duration of the study).
13. Subjects who have received investigational medications within 30 days of baseline.

This is a pilot study and has a small sample size.