The natural RaD (210Pb) concentration in man has been determined from measurement of RaF (210Po), by a silver plating method, in bone samples obtained from autopsy of unexposed children aged 0…13 years. The average RaD concentration found in 25 bone samples was 0,070 pCi/g ash. The concentration was 10% higher in trobecular than in cortical bones. Average RaD concentration in ribs 13% higher than that in femurs. Extremely high RaD contents were found in two caput femoris samples. Moreover an increase of RaD concentration according to age has been stated.