The Centers for Disease Control estimates that up to 15% of newly diagnosed cases of HIV infection are among people 50 years of age or older. By 2015, more than one-half of all HIV-infected individuals in the United States will be aged >50 years, not only from new cases but the greatly increased lifespan due to antiretroviral treatment (High 2012). Assessments of antiretroviral pharmacokinetics in older HIV-infected patients are very few, and there are no specific dosing guidelines for older patients in contrast to the general geriatric population (Hanlon 2009). Studies in older populations demonstrate decrements in liver metabolism and renal clearance, which may require dosage adjustments for drugs eliminated by the kidney. Additionally, decreased bioavailability due to changes in drug transporters alter pharmacokinetics of many drugs in older populations (Crawford 2010, Hilmer 2007). In a relevant study of older HIV-infected patients, trough lopinavir concentrations from 44 subjects showed that higher levels were associated with older age (Crawford 2010). The authors concluded that decreased lopinavir clearance was likely the reason for higher trough lopinavir concentrations in older patients. In a study of 51 patients receiving darunavir, a univariate analysis determined that every 10 years of age lowered clearance (CL/F) of darunavir by 19% (Dickinson 2011). Importantly, efavirenz has not been carefully evaluated in older patients, even though this is one of the most commonly prescribed agents, and is recommended in combination with other drugs as a preferred regimen by the Department of Health and Human Services (DHHS) and World Health Organization WHO (WHO 2010, DHHS 2012).