The aim of this study was to examine the relationship between situational and dispositional factors, the severity of sports injuries and mental health in athletes. According to the stress and injury model, some psychosocial factors can affect the incidence and severity of sports injuries through the intensity of the athlete’s stress response during a stressful situation such as demanding workouts or matches. This study used some measures that examine situational factors, such as perceived motivational climate of the team, symptoms of depression, anxiety and stress, perceived stress and social support, and measures that examine dispositional factors, i.e. goal orientation, emotional regulation strategies, affect, life satisfaction and mental health. The results obtained on a sample of 426 athletes indicate that there is only a significant, low negative correlation between the severity of sports injuries and positive affect. Thus, athletes who were absent for longer periods due to sports injuries experienced fewer positive emotions. Also, given the severity of the injury, it was found that athletes who suffered severe injuries and therefore missed 4 or more weeks of training and matches, perceive the motivational climate of the team as learning-oriented significantly lower than athletes who suffered minor injuries. In addition, significant differences in life satisfaction were obtained with respect to the severity of the injury experienced, with athletes who experienced severe injuries having significantly lower life satisfaction compared to athletes who experienced minor injuries. Furthermore, two hierarchical regression analysis were performed in two steps on a subsample of professional athletes to examine the contribution of situational factors as well as dispositional factors and injury severity in explaining their mental health. It was found that the length of absence due to injury significantly contributes to the explanation of the poorer mental health of professional athletes. Such a finding can be explained by the fact that this group of athletes was deprived of their primary source of income due to an injury, and thus their financial stability and consequently impaired mental health were called into question. Although not all the obtained results are in accordance with the expectations according to the stress-injury model, the previous results from the literature are inconsistent and point to the extreme complexity of sports injuries and the factors that cause them.