The aim of investigation was to refine mechanisms of chemotherapy adverse effects on salivary gland function. Material and methods. For 15 children between the ages of 12 to 17 years (11 boys and 4 girls) diagnosed with osteosarcoma before treatment, at days 7 and 14 of chemotherapy were measured unstimulated salivary flow rate, concentrations of potassium, sodium, calcium, phosphorus, total protein (TP), mucin and alkaline phosphatase (ALP) activity. The control group consisted of 15 (8 boys and 7 girls) healthy children of the same age. Results. Initially, patients had elevated TP content (5.6±3.2 g/l vs. 4.8±2.8 g/l), mucin (0.31±0.14 g/l vs. 0.23±0.13 g/l ) and ALP (37±12 U\l vs. 25±15 U/l) and decreased phosphate content of (9.1±6.1 mmol/l vs. 11.3±3.0 mmol/l). During chemotherapy potassium (15.6±4.8 mmol/l) and sodium 4.4±1.1 mmol/l levels did not change. Salivation rate uniformly increased from 0.81±0.33 to 0.99±0.38 ml/min and the calcium and phosphate concentration decreased from 1.9±1.1 to 1.2±0.4 and from 9.1±6.1 to 6.0±2.6 mmol/l respectively. TP and mucin levels rose to day 7 (8.0±5.5 and 0.42±0.21 g/l respectively), followed by reduction (3.8±1.6 and 0.30±0.12 g/l respectively) to day14, while ALP decreased to day 7 (18±11 U/l) and increased to day 14 (31±28 U/l). It correlates with the dynamics of mucositis clinical manifestations. Conclusion. Polychemotherapy weakly affects the transport of water and electrolytes in the salivary glands, while synthetic processes are broken to an appreciable extent.