Abstract: OBJECTIVE To observe the efficacy of Er Xian Decoction in treating the both kidney yin and yang deficiency type of late-onset hypogonadism in males (LOH). METHODS In accordance with the acceptance and exclusion criteria， 80 LOH patients were randomly divided into trial group and control group by a randomized controlled single-blind clinical trial and treated for 12 weeks. The trial group was treated with Er Xian Decoction， and the control group with testosterone undecanoate capsule. Compare the partial androgen deficiency in aging males(PADAM) scores， the levels of serum total testosterone (TT) and testosterone secretion index (TSI) of the two groups before treatment and after 4， 8 and 12 weeks of treatment. RESULTS The PADAM scores difference of the trial group between before and after 4， 8 and 12 weeks of treatment has significance in statistics (P<0.05). The TT level and TSI difference of the trial group between before and after 4， 8 and 12 weeks of treatment has significance in statistics (P<0.05). The difference was not statistically significant between the two groups in these indicators except after 4 weeks treatment (P>0.05). After the treatment， TCM syndrome scores in two groups decreased significantly compared with pre-treatment (P<0.05)， and the difference was not statistically significant between the two groups (P>0.05). CONCLUSION Er Xian Decoction could significantly improve the clinical symptoms of LOH with both kidney yin and yang deficiency and increase the serum TT level and TSI， and equivalent to the effect of testosterone undecanoate.