Objective: To investigate the possible association between untreated ADHD symptoms (as measured by the Adult ADHD Self-Report Scale) and persistent nonmedical use of prescription stimulants. Method: Multinomial regression modeling was used to compare ADHD symptoms among three groups of college students enrolled in a longitudinal study over 4 years: (1) persistent nonmedical users of prescription stimulants, (2) persistent users of marijuana who did not use prescription stimulants nonmedically, and (3) consistent nonusers of drugs. Results: ADHD symptoms were associated with being a persistent nonmedical user of prescription stimulants after adjustment for race/ethnicity, sex, socioeconomic status, and other illicit drug use. No associations were observed between ADHD symptoms and being a persistent marijuana user or nonuser. Conclusion: ADHD symptoms, and in particular inattention symptoms, appeared to be associated with nonmedical use of prescription stimulants. (Contains 2 notes and 3 tables.)