The aim of the study was the appreciation of the influence of a therapy with L-thyroxine on the metabolism and density of the osseous tissue (BMD) in children with an euthyroid diffuse and nodular goiter. The examinations included 50 children (5 boys and 45 girls). Mean age of the investigated group: 17 years, time of therapy 2-5 years. The daily dose of L-thyroxine was not higher than 1-2 microg/kg body mass. All the children were in clinical and hormonal euthyrosis. The control group consisted of 50 healthy children (12 boys and 38 girls), mean age 16,16 years. A correlation between the age of the children, TSH level and the markers of the osseous circle was not observed. The mean level of TSH was statistical significant lower in the examined group. In the examined group the level of PTH and ICTP in the blood serum was (PTH: 35.83+/-8.34 pg/m vs 37.21+/-7.17 pg/ml); ICTP (8.7+/-3.87 microg/l vs 15.11+/-5.7 microg/l) was lower in the control group but the difference was statistical not significant (p=0.07). The mean concentration of PICP in the investigated group was significant lower in comparison with the control group. The mean level ICTP between the examined and control group was statistical significant (p<0.05). The mean concentration of osteocalcine (OC) in the treated with L-thyroxine was statistical not significant.