Background and aims: Aging is accompanied by a progressive decline in serum testosterone. Evidence concerning the clinical manifestations of low serum testosterone levels is contradictory. We aimed to examine the age-related decline in testosterone and the possible clinical outcomes, including erectile dysfunction, prostatism, cognitive function, daily life activities, depression, and osteoporosis. Methods: One hundred and twenty men underwent comprehensive geriatric assessment. Testosterone and free testosterone levels were measured, geriatric assessment scales, International Index of Erectile Function (IIEF) and International Prostate Symptom Scale (IPSS) were performed, and bone mineral densities were determined. Results; The mean age of the 120 men was 73.8 +/- 5.90. A significant decrease in testosterone and free testosterone levels with increasing age was determined (p=0.021). It was also found that erectile dysfunction, as determined by IIEF (r=0.66, p < 0.001), and symptoms of prostatism determined by IPSS (r=-0.23, p=0.016), were significantly associated with low free testosterone levels. Laboratory parameters, obesity, osteoporosis, cognitive function, daily life activities, and cardiovascular diseases were not significantly different between groups with low and normal free testosterone levels. Conclusion: Age-related decrease in free testosterone may lead to erectile dysfunction and symptoms of prostatism in elderly men.