Abstract. Prosocial behavior is intended to benefit others rather than oneself and is positively linked to personality traits such as Agreeableness and Honesty-Humility, and usually negatively to the Dark Triad traits (i.e., Machiavellianism, narcissism, and psychopathy). However, a significant proportion of the research in this area is conducted solely on self-report measures of prosocial behavior. Therefore, the aim of this study was to investigate the relationship between prosociality and the basic (i.e., HEXACO) and dark personality traits, comparing their contribution in predicting both self-reported prosociality and prosocial behavior. Results of the hierarchical regression analyses showed that the Dark Triad traits explain prosociality and prosocial behavior above and beyond the HEXACO traits, emphasizing the importance of the Dark Triad in the personality space.