The primary aim of the current article was the evaluation of the factorial composition of the Aggression Questionnaire (AQ(29)) in the Greek population. The translated questionnaire was administered to the following three heterogeneous adult samples: a general population sample from Athens, a sample of young male conscripts and a sample of individuals facing problems related to substance use. Factor analysis highlighted a structure similar to the one proposed by Buss and Perry [Buss, A.F., Perry, M., 1992. The Aggression Questionnaire. Journal of Personality and Social Psychology 63, 452-459]. However, the refined 12-item version of Bryant and Smith [Bryant, F.B., Smith, B.D., 2001. Refining the architecture of aggression: a measurement model for the Buss-Perry Aggression Questionnaire. Journal of Research in Personality 35, 138-167] provided a better fit to our data. Therefore, the refined model was implemented in further analysis. Multiple group confirmatory factor analysis was applied in order to assess the variability of the 12-item AQ across gender and samples. The percentage of factor loading invariance between males and females and across the three samples defined above was high (higher than 75%). The reliability (internal consistency) of the scale was satisfactory in all cases. Content validity of the 12-item AQ was confirmed by comparison with the Symptom Check-List 90 Revised.