Various physiological/physical and psychological stressors in some firefighters lead to impaired physical and mental health, and the stigma against seeking psychological support is still present. There are numerous predictors of the mental health of firefighters, but group work cohesion stands out as one of the most important protective factors in the literature. The goal of this research, by combining quantitative and qualitative methodology, was to assess the mental health of Croatian professional firefighters and the stressfulness of the job, and to gain insights into what they think about seeking and availability of psychological help and the importance of group work cohesion. In the first part of the research, the DASS and SOOS-14 scales were used, 107 participants took part, while in the second part of the research, 8 focus groups were conducted within five professional fire departments. The results of quantitative methods indicate a lower prevalence of depression, anxiety and stress compared to the general population and moderate levels of occupational stress. A quarter of the participants reported impaired physical/mental health as a result of work demands, but only half of them requested/received psychological help. Five stressors that affect Croatian firefighters the most have been singled out. Qualitative methods were used to identify three main topics: occupational stress in firefighting, attitudes about seeking psychological support and group work cohesion. The participants recognized the importance of psychological support, but emphasized the stigma towards seeking it is still present and pointed out some shortcomings of the current system of providing psychological support to firefighters in Croatia. They made proposals for its’ improvement - the introduction of mandatory psychological support for all firefighters several times a year and after difficult interventions, and the organization of psychoeducational workshops. Work group cohesion was recognised as one of the most important factors in preserving the mental health and efficiency of the unit's work and they were mostly satisfied with it.