Abnormal blood lipid profiles may be observed both in HIV-infected individuals who are untreated and in those receiving highly active antiretroviral therapy (HAART). Besides maintaining optimal control of HIV replication and the preservation of immunity, treatment regimens ideally should have minimal or no metabolic side-effects. Nevirapine (NVP)-based HAART has beneficial effects on the lipid profile, in both treatment-näive and treatment-experienced patients, unlike protease inhibitor (PI)-based HAART. In antiretroviral (ARV)-naive patients enrolled in the Fat Redistribution and Metabolic Substudy (FRAMS) of the Atlantic Study, the NVP-containing regimen increased total cholesterol, high density lipoprotein (HDL) cholesterol concentration and particle size and apolipoprotein A1 (apo A1) levels at 24 weeks. The changes in HDL cholesterol plasma levels were demonstrated to be sustained in a subset of 98 FRAMS patients at 96 weeks. Switching from a PI-containing regimen to a PI-sparing regimen containing NVP has likewise been shown to favorably alter lipid profiles in two open label studies. In one study, one or more lipid profile parameters (total cholesterol, low density lipoprotein [LDL] cholesterol, LDL particle size, very low density lipoprotein cholesterol [VLDL1] HDL cholesterol, HDL particle size) had reverted to normal after 24 weeks in significantly more NVP-treated patients than PI-treated patients (69% versus 23%, p < .05). The 12-month results from the Barcelona PI Switch Study indicated that NVP improved lipid profiles over 12 months after PI-treated patients were switched to NVP. In conclusion, first-line NVP treatment is associated with a favorable lipoprotein profile, i.e., an increase in HDL-cholesterol and apo A1 plasma levels The lipid profile observed in patients who are switched from a PI-based regimen to a NVP-based regimen improves in a very similar fashion. These favorable lipid profiles may be of clinical benefit in reducing the risk for coronary artery disease in HIV-1 infected patients who are receiving long-term antiretroviral therapy.