This was designed as a cross-sectional study on 208 healthy men aged 15 - 45 years old randomly selected from Ha Noi and Ha Nam, to determine serum level of total testosterone by Electro-chemiluminescence Immunoassay (ECLIA). The result showed that serum level of total testosterone in men was 6,32 +/- 2,15 ng/ml, the concentrations were not different among age-specific groups (p 0,05) and between men from urban and rural area.