Aim. Optimization of the diagnosis of the initial stages of Legg-Calve-Perthes disease in children of 4-7 years old using biochemical and ultrasound methods. Materials and Methods. Patients aged 4-9 years (15 boys, 10 girls) complaining of morning pain in walking, contracture in the hip joint, lameness, were examined. The duration of the disease ranged from several days to 2-3 months. The control was a group of healthy children aged 4-9 years (n=22, 12 boys, 10 girls). Ultrasound of the hip joints was performed on Hitachi scanner (Japan) using a linear sensor with 7.5 MHz frequency. In the blood serum of patients, the follow-ing markers of resorption of the organic matrix of bone tissue were determined: the amount of sulfate sulfur, hexuronic acids (HAC), hexoses, hexosamines, sialic acids with calculation of their ratios: hexoses/hexuronic acids, hexoses/sulfate, sulfate/hexuronic acids, hexuronic ac-ids/hexosamines. Besides, concentration of electrolytes was determined in serum: total calcium and chloride ions and inorganic phosphate. On the basis of these fata, the system index of elec-trolytes SIE=ССа.CCl/CPO4 was calculated. The concentrations of parameters obtained in the ex-amination of 25 healthy children of 4 to 7 years of age were taken for norm. Results. In children with duration of the disease from several days to several weeks, an ultra-sound scan along the neck of the femur revealed thickening of the joint capsule to 0.73 (0.7:0.77) mm. With the progression of the pathological process, separate lumpy formations were visualized in the region of the subchondral plate of the femoral head in the position of abduction of the limb and internal/external rotation, which indicated the appearance of initial destructive changes in the region of the subchondral plate of the femoral head. Using biochemical methods, besides increase in the concentration of organic matrix degradation markers, there were also determined increase in the extent of sulphatation of the organic matrix and insignificant alterations of the content of separate electrolytes. Conclusions. The use of biochemical and ultrasound research methods allows optimization of the diagnosis of the initial stages of Legg-Calve-Perthes disease.