Purpose: The main goal of this research was to establish differences in self-assessment of preparedness of Greco-Roman wrestlers in different age groups before a competition. Methods: The sample of subjects consisted of Greco-Roman wrestlers (n=223) divided into three age groups (cadets n=76; juniors n=69; seniors n=78). Self-assessment of prepared-ness was determined immediately before oficial weighing (approximately 16 hours before oficial weighing) using a survey questionnaire on the Likert scale of 1 to 5. Descriptive sta-tistic parameters were present. The wrestlers’success was determined by analysis of oficial bulletin from national championships. The correlation between self-assessment of prepar-edness and success was determined by a linear regression analysis. Statistically significant differences between the groups were determined by the Mann-Whitney test. Results: Most cadets (35.5% of subjects) estimate that they are completely prepared for a competition comparing to juniors. Seniors and juniors carefully evaluated preparedness for a competition. Seniors (42.3% of subjects) estimate that they are somewhat prepared, while juniors (43.5% of subjects) estimate that they are highly prepared for a competition. Furthermore, results of linear regression indicate relation (R = 0.203; p = 0.002) between self-assessment and success of Greco-Roman wrestlers. In addition, statistically significant differences between cadets and juniors (p = 0.033) were confirmed as well as between ca-dets and seniors (p = 0.001) in variable self-assessment of preparedness for a competition. Conclusion: Statistically significant relation between self-assessment and success indicates that wrestlers with a high level of self-assessment have better success as well as self-confi-dence in wrestling competition. The differences between age groups of Greco-Roman wres-tlers in variable self-assessment of preparedness emphasize importance of realistic and achievable goals in young age groups of wrestlers. Setting unrealistic goals can lead to frustrations or giving up on practicing wrestling. Therefore, individual approach to the mental preparedness of young wrestlers before a competition is very important, especially setting and realization of achievable goals. In this way, positive experience from a competition will raise the level of self-confidence in young age wrestlers.