The effects of stimulant drugs on risk-taking behavior vary across individuals, even in healthy samples. These differences could relate to personality, which may share common mechanisms with drug effects or impulsive, risk-taking behavior. The current study investigated the role of temperament and gender in the effects of amphetamine on risk taking. Forty healthy men and women, aged 18 to 35, completed the Balloon Analogue Risk Task (BART; Lejuez et al., 2002) with three reward values after ingesting placebo or d-amphetamine (10, 20 mg). They completed the Multidimensional Personality Questionnaire Brief Form (MPQ-BF; Patrick et al., 2002), with three main scales: Trait reward sensitivity (Agentic Positive Emotionality; AgPEM), impulsivity (Constraint; CON), and negative affect (Negative Emotionality; NEM). d-Amphetamine (20 mg) decreased risk behavior in low AgPEM males, but increased risk behavior in high AgPEM males, producing positive correlations with AgPEM in men (r >or= +.55, p<.05). The drug did not affect risk-taking in women. There was evidence of discriminant validity between the AgPEM, NEM, and CON dimensions and behavioral responses to amphetamine. Implications for treatment and addiction are discussed. (c) 2008 APA, all rights reserved.