Epidemiological data indicate that nonmedical use of prescription stimulants has increased over the past decade. However, little is known regarding the source of the misused stimulants and whether different sources correspond to differences in risk profiles and associated social and health problems.Data from the 2006 to 2011 National Survey on Drug Use and Health were used. A total of 4945 participants who used prescription stimulants nonmedically and also reported their source of misused stimulants were categorized by the source: friend/relative, physician and illegal. Logistic regression models compared the socio-demographic, mental health and behavioral problems, and stimulant use-related problems (onset, recency, frequency, severity) according to the source of the misused stimulants.The most common sources of stimulants were friends/relatives, followed by physicians and illegal sources. Compared to participants reporting friends/relatives as the source, participants reporting an illegal source were more likely to be male, unemployed, have less than a high school education, a history of criminal behavior and an earlier age of use onset. Participants reporting a physician source were more likely to have mental health problems and mental health service use. Higher odds of past-month stimulant use, frequent use (≥ 10 days per year), drug dependence and substance service use were found in individuals reporting physician and illegal sources.Identifying the source of misused stimulants may be useful in detecting distinct subgroups of nonmedical prescription stimulant users, which may inform development of tailored prevention and treatment programs and contribute to individual treatment planning.