[BACKGROUND - Patients with cow's milk allergy (CMA) form a potential risk group for osteopenia, because their milk-free diet usually has a low calcium content.The study analyses various parameters of bone mineralization in CMA children. PATIENTS AND METHODS - Twenty-seven CMA patients (mean age: 4.3 years, range: 3-8 years) were enrolled in the study.Transient sensitivity to cow's milk was observed in 20 of 27 patients. During the milk-free diet period (mean duration 11.8 months) children were fed by extensively hydrolysed or soy-based formulas. Seven patients still required a cow's milk free diet at the time of the study. Serum levels of Na, K, Cl, Ca, P and Mg ions, as well as of alkaline phosphatase (AP), parathyroid hormone (PTH), osteocalcin and beta-crosslaps were determined for all 27 patients.The values were compared to those of 20 healthy age-matched controls. Bone mineral densities (BMDs) of CMA patients were also measured. RESULTS - The AP and PTH levels were higher in CMA patients than in the control group (AP: 610.2 U/l vs 499.7 U/l, p<0.01; PTH: 1.56 pmol/l vs 0.83 pmol/l, p<0.03), but all values fell in the normal range.The osteocalcin level was similar in the two groups, and the beta-crosslaps was lower in CMA patients than in the controls (0.92 vs 1.47 ng/ml, p<0.001).There was a positive correlation between both AP and osteocalcin and AP and beta-crosslaps levels.The mean Z score of bone mineral density in patients with CMA was -0.6. In 10 cases the Z score was below -1, which was associated with a significantly elevated PTH level compared to the group of patients with a Z score above - 1 (2.24 pmol/l vs 1.16 pmol/l, p<0.03). CONCLUSION - In children with CMA on a cow's milk free diet, slight disturbances of bone mineralization were observed, therefore, osteodensitometric check-up of these children is recommended.]