The aim of this research is to examine the connection between mental toughness of athletes and their personality traits. The research sample consists of 100 athletes who participate in sports competitions. Mental Toughness was measured by Sports Mental Toughness Questionnaire (SMTQ), HEXACO personality traits by HEXACO-60. The results showed statistically significant positive correlations between honesty on one side and self-confidence (r= 0,31, p<0,01), consistency (r= 0,45, p<0,01), control (r= 0,34, p<0,01) and overall mental toughness (r= 0,46, p<0,01) on other. There were also statistically significant positive correlations between extraversion and self-confidence (r = 0,39, p <0,01), consistency (r = 0,62, p <0,01), control (r = 0,30, p <0,01) and total mental toughness (r = 0,44, p <0,01). Statistically significant positive correlations were also found between conscientiousness and self-confidence (r = 0,30, p <0,01), consistency (r = 0,58, p <0,01), control (r = 0,23, p < 0,01) and total mental toughness (r = 0,52, p <0,01). Statistically significant negative correlations were found between emotionality on one hand and self-confidence (r= -0,37, p<0,01), consistency (r= -0,46, p<0,01), control (r= -0,46, p<0,01) and overall mental strength (r= -0,54, p<0,01) on the other. While correlations of agreeableness and openness to experience on one side and self-confidence, consistency, control, and overall mental toughness on the other were not statistically significant. Multiple regression analysis was performed with the aim of predicting the mental toughness of athletes based on their personality traits. Of the total variability of mental toughness, 34% of variability can be explained based on personality traits of athletes. The results showed that statistically significant predictor of mental toughness was emotionality. Partial contributions of other personality traits were not statistically significant. This study contributes to the understanding of which personality traits of athletes contribute to mental toughness, a coping mechanism when faced with challenges and reacting in competitive situations.