Abstract Subjective effects of atropine sulfate injections were assessed in normal volunteers (n=10), as one portion of a 3-part study (behavioral, subjective and physiologic effects of atropine). Each volunteer was given 0, 2 or 4 mg/70 kg atropine sulfate intramuscularly according to randomized block sequences on different test days. To assess psychoactivity of atropine, the Single Dose Questionnaire (SDQ) and the Addiction Research Center Inventory (ARCI) were given 1 hr before and 1 hr following drug injections. Data from the SDQ indicated that atropine produced significant discriminable effects but did not elevate scores on a drug liking scale. Data from the ARCI indicated that atropine produced significant sedative-like effects (pentobarbital-chlorpromazine-alcohol scale). Taken together, the data from the psychometric instruments confirms that atropine is a drug of relatively low abuse potential.