Firefighters are exposed to several health risk factors, and therefore there is great concern about the health of these professionals, especially the cardiometabolic aspects. Late-onset hypogonadism (HIT), characterized by low testosterone levels and the presence of signs and symptoms such as fatigue, lack of libido, and reduced physical performance, may be associated with higher cardiometabolic risk and lower quality of life (QoL) in these professionals. . In addition, low testosterone levels in men are commonly associated with other conditions where there is an increased cardiovascular risk, such as metabolic syndrome (MS) and obesity (Ob). However, HIT is poorly investigated, and its prevalence is unknown in firefighters. In an enriched sample, we randomly selected 328 military firefighters who completed bloodwork and answered a questionnaire that included questions about physical activity, QOL, signs and symptoms of hypogonadism, and sleep quality. The inverse probability weighting technique was used to estimate the prevalence of HIT, MS, and Ob. Data were described using median and quartiles (non-parametric data), and differences were considered significant when p<0.05. The strength of the association between the prevalence of HIT, MS, Ob, and cardiorespiratory fitness (CRF) was analyzed using the chi-square test and the odds ratio (OR) with the respective 95% confidence interval. The correlation (Spearman) between total testosterone levels (TT) and the four domains of QOL, age, body mass index (BMI), CRF, and Framingham cardiovascular risk score (FRS) was analyzed. The estimated prevalence of HIT, MS, and Ob was 3.2%, 17.0%, and 16.9%, respectively. There was a significant age-corrected association between HIT and MS (OR 21.3; 7.0-64.2) and Ob (OR 41.7; 9.2-189.9). There was a significant correlation between TT levels and age (rs = -0.35; p<0.01), BMI (rs = -0.46; p<0.01), VO2max (rs = 0.45; p<0.01), and ERF (rs = -0.42; p<0.01). As for QOL, there was a significant correlation only with the physical domain (rs = 0.20; p<0.01). There was no significant correlation with sleep quality (rs = -0.05; p=0.38). An original finding of this study was identifying the prevalence of HIT in firefighters and its associated factors. Despite the low prevalence of HIT, there was an association with significant cardiovascular risk factors such as metabolic syndrome and obesity that can be deleterious to the health of military firefighters. The prevalences found and their associations are especially worrying in this population, given the routine physical and emotional demands inherent to the profession and its high health risk.