Interpersonal trust is an integral component of the patient-provider relationship and has been associated with patient adherence to medications. Studies suggest African Americans may have lower levels of trust in their health care providers than non-Hispanic Whites. This study examines the association between trust in one's primary care provider (PCP) and antiretroviral (ARV) adherence among 175 patients at an urban HIV clinic. Interviews elicited participants' level of trust in their current PCP using a multiple-item trust scale and assessed ARV adherence with a seven-day recall questionnaire. Logistic regression was used to ascertain the effect of trust in PCP on ARV adherence. High trust in PCP was significantly associated with increased odds of ARV adherence compared with low trust (adjusted odds ratio, 2.67; 95% confidence interval, 1.24 to 5.76; p=.01). Enhancing trust in PCPs may be a good target for interventions to improve ARV adherence, particularly among African American patients.