In this study, we investigated the essential criteria for late-onset hypogonadism (LOH) syndrome based on the presence of symptoms associated with low testosterone levels in Han Chinese men. Blood tests for total testosterone (TT) and sex hormone-binding globulin (SHBG) were performed, and the aging male symptoms (AMS) questionnaire was conducted in a randomly selected cohort composed of 944 Chinese men aged 40 to 79 years from nine urban communities. Three sexual symptoms (decreased ability/frequency of sexual activity, decreased number of morning erections, and decreased libido) were confirmed to be related to the total and free testosterone levels. The thresholds for TT were approximately 12.55 nmol l(1) for a decreased ability/frequency to perform sex, 12.55 nmol l(1) for decreased frequency of morning erections, and 14.35 nmol l(1) for decreased sexual desire. The calculated free testosterone (CFT) thresholds for these three sexual symptoms were 281.14, 264.90, and 287.21 pmol l(1) , respectively. TT < 13.21 nmol l(1) (OR = 1.4, 95%CI: 1.0-1.9, P = 0.037) or CFT < 268.89 pmol l(1) (OR = 1.5, 95%CI: 1.1-20, P = 0.020) was associated with an increase in the aforementioned three sexual symptoms. The prevalence of LOH was 9.1% under the criteria, including all three sexual symptoms with TT levels < 13.21 nmol l(1) and CFT levels < 268.89 pmol l(1) . Our results may improve the diagnostic accuracy of LOH in older men.