Prescription medication borrowing can result in adverse health outcomes. We aimed to study the patterns of borrowing prescription medications in an adult urban population seeking healthcare in the outpatient, emergency, and inpatient units of an urban medical center. Participants indicated whether they (1) had a primary care doctor, medical insurance, a prior history of substance abuse, psychiatric disorders, or chronic pain; and (2) had borrowed a prescription medication. If so, they noted the medication obtained, source, frequency of use, and reasons why they had not obtained a prescription from a licensed medical provider. Of the 641 participants, most were African American (75%), urban residents (75%), high school educated or less (71%), and lacked full-time employment (68%). Many had health insurance (90%) and had recently seen their primary medical provider (75%). Eighteen percent reported ever borrowing a prescription medication. On multivariate analysis, history of chronic pain was marginally associated with increased medication borrowing (odds ratio [OR] = 1.58) while having Medicare insurance (OR = 0.436) or a primary care medical provider routinely ask about medication usage (OR = 0.589) were significantly associated with decreased medication borrowing. The most commonly obtained medications were for pain (74%), usually in the form of opioids, and were obtained from a family member (49%) or friend (38%). Thirty-five percent of those who borrowed medications did so more than once a year, with lack of convenient access to medical care the most frequently cited reason for use (67%). Only a third of those who borrowed medications had informed their primary medical providers of the behavior. In conclusion, borrowing prescription medications is a common behavior in the population studied. Further research is warranted into interventions to reduce such use, especially the impact of methods to improve the convenience of contacting licensed medical providers.