To evaluate the consequences of puberty on calcium (Ca) metabolism, we measured Ca kinetic parameters in 43 healthy girls 1-60 months post menarche. There was a close relationship between the logarithmic transform of the number of months post menarche and the bone Ca deposition rate (Vo +) (r = -0.90, P < 0.001). Using multiple regression analysis with the logarithmic transforms of chronological age and months post menarche as independent parameters, we found that the number of months post menarche was more significantly correlated with Vo + (t = -7.4, P < 0.0001) than with chronological age (t = -3.1, P = 0.003). A longitudinal study of 17 girls demonstrated a peak Vo + approximately 8 months before menarche, with a decrease in Vo + after menarche. These studies indicate that the peak time for bone Ca deposition is in the premenarcheal and perimenarcheal time period. The close correlation between Vo + and months post menarche demonstrates the importance of puberty in consideration of bone Ca metabolism in girls.