The paper gives the results of a study of the levels of glycosaminoglycans (GAG) and hydroxyproline (HOP) in 87 apparently healthy individuals of both sexes, aged 19 to 60 years. There is a decrease in the levels of GAG, total HOP, and peptide-bound HOP with advanced age. These indices are higher in subjects less than 45 years old than in those over the age. The found age differences are comparable with higher serum hyaluronidase and collagenolytic activities in subjects younger than 45 years than in those over the age 45 years. Collagen metabolism occurs more intensively in young subjects (under 45 years of age) than in old ones (over 45). There are also gender-related differences: the men had higher levels of GAG and peptide-bound HOP and serum hyaluronidase activity than the women, which suggests that the metabolic rates of collagen and proteoglycans are higher. This difference is complimented by the qualitative characteristics of the process: there is a preponderance of the synthesis of collagen over its degradation with the accelerated degradation of proteoglycans in the young men. In Rh-positive subjects, the content of GAG was 22-fold higher than that in Rh-negative ones.