The bone mineral contents（BMC） of radius and ulna of 7972 individuals of 4-90 years old living in Shanghai were measured by GMY-1 bone mineral detector

which is based on γ-ray absorptiometry technique. The results obtained showed that the BMC at 4-19 years old increased yearly

the growing rate being quicker in males than in females. The BMC of 20 to 29 years old group grew slowly and remained relatively constant at years 30-39. Then it started to fall down when the age was over 40 years old. The speed of reduction in females was twice or thrice times quicker than that in males. The BMC was obviously decreased when females were above 50 years old and males were above 60 years old.