Aim. Researchers have proved detrimental effect of stressful life events on physical and mental health. On the other hand psychologists have identified a number of personality variables that exert stress-buffering effect. According to Personality Systems Interactions (PSI) theory, stressful life events (differentiated into demands and threats) are expected to reduce subjective well-being when the ability to self-regulate affect is impaired. The aim of the present research was to verify a hypothesis that in the stressful demanding situation action oriented individuals, due to their high self-regulation competences, will display less mental health problems than state oriented individuals. Methods. The group of participants included 92 persons at the age of 18-19. The research had been carried out one month prior to the high school finals. The Action Control Scale (ACS-90) was used to measure self-regulation competences, perceived stress was assessed with the Perceived Stress Scale (PSS-10), Goldberg's General Health Questionnaire (GHQ-28) was administered to assess emotional ill-being and psychosomatic symptoms. Results. Higher levels of perceived stress were associated with significantly higher indexes of emotionaill being and somatic symptoms. However, the influence of perceived stress on psychological well-being seems to be moderated by self-regulation competences. State-oriented individuals showed substantially more mental health problems than action-oriented individuals when perceived stress increased. Conclusions. The relation between perceived stress and mental health problems varied as a function of self-regulation competences. The findings suggest the importance of developing self-regulation competences to minimize the risk of harmful effect of stressful situation on mental and physical health.