OBJECTIVE To review the pharmacology, virology, pharmacokinetics, resistance profile, clinical efficacy, safety, and drug interactions of atazanavir. DATA SOURCES A PubMed and NLMGateway search (1966–June 2004) utilizing the key words atazanavir and BMS-232632 was performed. Abstracts from scientific meetings, including the Conference on Retroviruses and Opportunistic Infections, International AIDS Society Conference on HIV Pathogenesis and Treatment, Interscience Conference on Antimicrobial Agents and Chemotherapy, and the Infectious Diseases Society of America, were also reviewed. STUDY SELECTION AND DATA EXTRACTION All publications and meeting abstracts were reviewed, and information relevant to the formulary decision-making process was selected. DATA SYNTHESIS Atazanavir is a once-daily protease inhibitor (PI) that received approval by the Food and Drug Administration in June 2003. In clinical trials in antiretroviral (ARV)-naîve patients, atazanavir had efficacy similar to that of efavirenz or nelfinavir. In ARV-experienced patients, atazanavir was inferior to lopinavir/ritonavir unless atazanavir was coadministered with low-dose ritonavir. Following failure of an atazanavir-containing regimen in ARV-naîve patients, a unique I50L mutation was seen. Atazanavir resistance is likely when resistance to ≥3 PIs is present. Atazanavir can cause increases in unconjugated bilirubin levels, which rarely leads to jaundice or scleral icterus. In contrast to comparators, atazanavir did not negatively impact the lipid profile. Similar to other PIs, atazanavir is metabolized by and inhibits CYP3A at clinically relevant concentrations; therefore, many potential drug interactions exist. CONCLUSIONS Atazanavir is a once-daily PI that, unlike other PIs, does not negatively impact the lipid profile. Atazanavir may be particularly desirable in patients with hyperlipidemia or other coronary artery disease risk factors.