Introduction: Androgen decline in the aging man has become a topic of increasing clinical relevance worldwide, as the reduction in testosterone levels has been reported to be accompanied by loss of muscle mass, accumulation of central adiposity, impaired mobility and increase risk of bone fractures. Although well-established in studies conducted in developed countries, progressive decline in serum testosterone levels with age has been poorly investigated in Brazil. Aim: To determine the pattern of blood testosterone concentrations decline with age in a cohort of Brazilian healthy military men. Materials and Methods:We retrospectively reviewed data on serum testosterone measurements of healthy individuals that had undergone a routine check-up at the Military Biology Institute. Blood samples were obtained early in the morning, and total testosterone concentration was determined using a commercial chemoluminescent immunoassay. Mean values were analyzed in five age groups: ≤ 40, 41 to 50, 51 to 60, 61 to 70, and > 70 years. Main Outcome Measure: Mean total testosterone levels. Results: 1,623 subjects were included in the analysis; mean age was 57 years (24 to 87), and mean testosterone level was 575.5 ng/dL (25.0 to 1308.0 ng/dL). The evaluation of age-related changes in total testosterone levels revealed a progressive reduction in serum levels of this hormone with increasing age. Testosterone levels below 300 ng/dL were reported in 321 participants, a prevalence of nearly 20% in the study population. Conclusion:In agreement with other findings, a reduction of total testosterone levels with age was reported for healthy Brazilian men.