Abstract: With the rapid aging progression for the human being，more concern was focused on the
research of late鄄onset hypogonadism（LOH）. In the review article，the mechanism and epidemiological research
on LOH is sumarized. The mechanism of LOH is the combinated effects of primary and secondary factors，
which achieved by many pathways to damage the secretion and bio鄄activity of androgen including the androgen
level and androgen receptor（AR）. Morbidity，susceptibility and risk factors are reviewed including diseases
and medication，obesity，untoward life style，environmental and genetic factors，psychological factor，social鄄
economic factors and cultural level.

Key words: Men, Age factors, Hypogonadism, Testosterone, Epidemiology, Etiology