In vivo assessment of bone mineral density (BMD) and bone mineral content (BMC) indices gives an objective description of the possible rates of bone loss during aging and various diseases, as well as response to treatment by various drugs, affecting bone metabolism. This study was conducted on 376 Wistar rats of both genders, divided into 12 age groups using the method of dual-energy X-ray absorptiometry. Studying the parameters of BMD and BMC depending on age and sex has found no bone mass «peak» in rats of both sexes. Bone mineral density indices were increased in both male and female rats during growing, more pronounced in males. These differences are noted in all age groups of animals. Moreover, we have established age and gender particularities of BMC indices in different parts of the skeleton. In female rats, a significant increase of BMD and BMC parameters have been detected in age from 1.5 to 2 months (33 %), from 2 to 3 months – by 12.5 %. In males, the increase of BMD indices was found to happen 1 month later and it was less pronounced (from 2 to 3 months – 27 %, from 4 to 5 months – 5 %). In other age periods, the dynamics of BMD indices had only an upward trend, but significant differences different groups were not established. Our results of BMD and BMC indices and their age and gender features can be used for further research in osteology as reference data for modeling of experimental osteoporosis in rats and study of response to the use of different antiosteoporotic drugs.