Mental health refers to a state of well-being in which a person is able to realize their potential and cope with various life stresses. It is related to the subjective feeling of well-being and is an integral part of overall health. Self-esteem plays a crucial role in mental health, and it influences how an individual will respond to challenges and how they will cope with them. This study examined the connection between mental disorders and the level of self-esteem. The fundamental scientific hypothesis is that the level of self-esteem is related to the development of anxiety, depression, and/or stress. The research methodology includes the implementation of a survey questionnaire among patients of the Daily Hospital of the Psychiatric Clinic of Clinical Hospital Dubrava and individuals who have never been involved in any form of psychiatric treatment. The research results indicate a higher number of individuals with low self-esteem in the treated group compared to the untreated group. Additionally, individuals with low levels of self-esteem exhibit more pronounced symptoms of anxiety, depression, and/or stress than those with high self-esteem. This work contributes to understanding the determinants of mental health and to better understanding of illnesses, thus achieving the best approach to treatment and prevention of the mentioned mental disorders in healthy individuals.