This study aimed to assess firefighters' mental health indicators and what it was influenced by, highlighting differences between males and females. The study was exploratory and based on qualitative and quantitative methods. Firstly, indicators such as general mental health, depression, stress, anxiety, hopelessness, suicide ideation and alcohol use pattern were measured with the use of valid psychological tests. The sample comprised 303 firefighters: 277 males and 26 females. After that, 37 out of the total were interviewed (18 males and 19 females). Finally, their answers were evaluated using content analysis technique. The psychological indicators showed prevalence of depression, stress and general mental health higher among females than males. The men's and women's answers content were differed on their complaints about work, private and social lives as well as on their consequences perception on health and life at large. These results indicated that either work or private and social life probably affects firefighters' mental health in a non-hierarchical and complex way. Likewise, work, private and social lives probably affect each other dynamically.