The measurement of serum osteocalcin is a new sensitive and specific method in the evaluation of calcium metabolism disorders. We established the normal values of healthy adult Hungarian women (n = 111, age: 20-86 yrs, mean: 47 yrs) and men (n = 70, age: 20-88 yrs, mean: 42 yrs) by radioimmunoassay method developed at our institute. Serum osteocalcin levels are constant between 20-50 yrs (7,8 +/- 2,4 ng/ml) while the values are significantly higher after 50 yrs of age (11,0 +/- 4,6 ng/ml) and remain constant afterwards. A correlation might be supposed between this elevation around 50 and bone loss around menopause. Serum osteocalcin values of men are constant with aging (11,0 +/- 3,9 ng/ml).