Background / Aim. The most famous instrument for measuring psychological mechanisms of defense is the DSQ-40 (Defense Style Questionnaire), which has been increasingly used in our country. In Serbia empirical norms for male adolescent population and for elderly male adults were established. The aim of this study was psychometric evaluation of the short version of the Defense style questionnaire (DSQ-40) on a Serbian male middle-age non-clinical sample. Methods. Internal consistency, factor structure and discriminant and concurrent validity of the DSQ-40 were studied in 284 high selected male professional military personnel aged 23 to 53 years (35.09±7.21). Results. Alfa Cronbach coefficients revealed a high internal consistency for the entire scale, which confirms the compactness and high reliability of this questionnaire (ICC = 0.724; p <0.01). Discussion. Evaluation of Serbian version of DSQ-40 confirms intraclass highly significant coefficients of correlation Conclusion: The present findings support the applicability of the Serbian version of DSQ-40.