The 6beta-hydroxycortisol/cortisol ratio was measured in 52 children aging 1.1-14.0 years. The maximum increment in this ratio occurred in the age interval of 1.1-2.0 years. During this period, the regression coefficients in the linear (r=0.57; p=0.044) and nonlinear logarithmic models (r=0.56; p=0.049) were similar. At the age of 10-14 years, the examined ratio attained 19.17+/-17.79.