Regular intensive training associated with mental and physical effort can lead to overreaching of young elite athletes. The main purpose of this study is to map theoretical bases to examine the role of selected personality traits in the context of overtraining syndrome in young elite athletes. To examine possible relationships between overtraining and selected personality traits the study uses following methods: Big Five Inventory (BFI-44), Profile of Mood States questionnaire (POMS). In relation to the lack of rest, insufficient regeneration, stress and load before and during competitions, the risk of overtraining syndrome increases. Chronic fatigue, underperformance, inability to compete, sleep disturbances and mood disorders can be considered as the most significant symptoms of developed overtraining syndrome in young elite athletes. Athlete’s personality plays an important role in his sport career. Certain personality traits contribute to achieve positive results in sport. Nevertheless the relationship between personality traits and sport performance can be reverse. Achieving higher performance, experiencing success and life changes associated with sport career can lead to a modification of elite athlete’s personality. Personality traits differ among athletes and physically inactive population. Differences can be also identified in athletes engaged in individual and team sports.