['Alterations in serum lipids and an increased risk of myocardial infarction have been associated with HIV-1 infection and its treatment.', 'Lipoprotein subclasses were measured by nuclear magnetic resonance spectroscopy in frozen plasma samples from participants in the Multicenter AIDS Cohort Study. The effects of HIV-1 infection, antiretroviral therapy, and other factors on median particle concentrations were examined using quantile regression.', 'Fasted samples were tested from 1082 men, including 609 HIV-seronegative and 473 HIV-1-infected men. Compared with HIV-seronegative men, HIV-1-infected men on antiretroviral therapy had an atherogenic phenotype with higher numbers of very low density lipoprotein and small low-density lipoprotein particles and lower numbers of high-density lipoprotein and large low-density lipoprotein particles. HIV-infected, antiretroviral-naive men had significantly lower high-density lipoprotein and small low-density lipoprotein particle concentrations compared with the HIV-seronegative men. Among men on antiretroviral therapy, the atherogenic phenotype was most pronounced in men with a good clinical status.'] Is antiretroviral therapy associated with an atherogenic lipoprotein phenotype among HIV-1-infected men in the Multicenter AIDS Cohort Study?