© 2015 European Society of Endocrinology Printed in Great Britain. Aim: The age-specific population profiles in men of circulating testosterone and its two bioactive metabolites dihydrotestosterone (DHT) and estradiol (E2) across the adult lifespan and its determinants are not well described. Objective: Our objective was to deduce smoothed age-specific centiles of circulating testosterone, DHT, and E2 in men using pooled data from population-based studies in three Australian cities from liquid chromatography-mass spectrometry steroid measurements in a single laboratory. Design, setting, and participants: We pooled data of 10 904 serum samples (serum testosterone, DHT, E2, age, height, and weight) from observational population-based studies in three major cities across Australia. Main outcome measures: Age-specific smoothed centiles for serum testosterone, DHT, and E2 in men aged 35-100 years were deduced by large sample data analysis methods. Results: We found that serum testosterone, DHT, and E2 decline gradually from ages 35 onwards with a more marked decline after 80 years of age. Higher weight, BMI, and body surface area as well as shorter stature are associated with reduced serum testosterone, DHT, and E2. Conclusions: Among Australian men, there is a gradual progressive population-wide decline in androgen status during male aging until the age of 80 years after which there is a more marked decline. Obesity and short stature are associated with reduced androgen status. Research into the age-related decline in androgen status should focus on the progressive accumulation of age-related comorbidities to better inform optimal clinical trial design.