The aim: To research the indicators of teachers’ mental health in a destabilizing organization of professional activities. Materials and methods: The study was conducted at the Poltava M. V. Ostrogradsky Regional Institute of Postgraduate Pedagogical Education, Poltava V. G. Korolenko National Pedagogical University, Volodymyr Vynnychenko Central State Pedagogical University and Poltava State Medical University in 2018-2020. The sample size of 1817 respondents (Ukraine) included 388 men and 1429 women aged 20 to 57 years. The following methods were used: “Scale of threats to occupational health” (Dziuba, 2015) and “Scale of subjective well-being” (Sokolova, 2007) adapted by T. Dziuba. The study used mathematical and statistical analysis (descriptive statistics, correlation analysis) using IBM SPSS Statistics (version 21.0). Results: It was found that an unstable level of emotional comfort is dominant (57.2%). This is shown by the following indicators: “self-assessment of mental health” 61.0%, “tension and sensitivity” 54.3% and “signs of psychiatric symptoms” 53.0%. Correlation analysis revealed a significant negative impact of the threat factors “daily and weekly overtime” (p <0.01) and “overwork” (p <0.01) on mental health. There is an increase in emotional discomfort in a situation of daily and weekly overtime and overwork. There is a positive correlation between the teachers’ mental health and the indicator “significance of the professional environment” (p <0.01). Conclusions: The study showed that teachers’ mental health in Ukrainian educational organizations is characterized by unstable emotional comfort and increased emotional discomfort, which is a consequence of unbalanced (destabilizing) working conditions: overwork, overtime. The obtained data motivates the need to conduct targete psychotherapeutic and corrective work with teachers who demonstrate professional distress.