The paper described the study of serum - hormone levels by radioimmunoassay in 525 patients with male sexual insufficiency. The results showed that testosterone （T） level in 50 normal cases were 501. 0±108. 0ng/dl

but serum FSH

LH and PRL were 13. 6±8. 2mIU/ ml

7.8 ± 5. 5mIU/ml

15.97 ±5-43ng/ml respectively. 15 cases of genetype with klinefelter’s syndrome are all 47

XXY . No significant difference were noted in the serum T levels between klinefelter’s syndrome and normal controls

but the serum FSH was significantly increased （58. 78±22. 07mIU/ml）. If the level of T falls and FSH and LH rise the sterility mostly results from testical diseases. If T

FSH and LH are all normal

in most cases the sterility results from obstructed aspermia. If the PRL rises and T

FSH and LH are all in lower values it would be possibly hypogonadotrophinmia. If T is low

FSH and LH rises

the under development of testes should be considered.