Inclusion Criteria:

Main inclusion criteria for the study are:

1. HIV-1 infected adults, men and women at least 18 years of age.
2. 3-class (NRTI, NNRTI, and PI) treatment-experienced (min of 3-months duration for each class) with resistance to more than one PI (on screening resistance testing). NNRTI-naïve patients who have genotypically documented NNRTI-resistance mutations on past or screening resistance testing would be eligible.
3. CD4+ T lymphocyte count >=50 cells/mm3.
4. HIV-1 viral load >=1,000 copies/mL at screening.
5. The ARV study treatment regimen must consist of TPV/r in combo with an OBR of 2-4 agents: N(t)RTIs (NRTI or NtRTI), enfuvirtide (ENF), and/or, where available, a trial approved EAP investigational agent.
6. Acceptable screening laboratory values that indicate adequate baseline organ function.
7. Acceptable medical history with a chest X-ray without evidence of active disease and an ECG without clinically important abnormalities within one year of the study.
8. A reliable method of barrier contraception will be used by all female patients who are of childbearing potential.

Exclusion Criteria:

Main exclusion criteria for the study are:

1. Known hypersensitivity to the tipranavir or ritonavir.
2. ARV medication naïve.
3. Genotypic resistance to TPV (defined as a TPV mutation score >7).
4. Patients on recent drug holiday, defined as off ARV medications for at least 7 consecutive days within the month prior to screening.
5. Prior tipranavir use.
6. Inability to adhere to the requirements of the protocol.
7. Patients with prior history of hemorrhagic stroke or intracranial aneurysm.
8. Patients with a history of ischemic stroke, neurosurgery or skull trauma within 4 weeks prior to screening.
9. History of Progressive Multifocal Leukoencephalopathy, Visceral Kaposi's Sarcoma, and/or any malignancy.
10. Any AIDS defining illness that is unresolved, symptomatic or not stable on treatment for at least 12 weeks at screening visit.