The article describes a case of vitamin D intoxication (cholecalociferol) in a premature baby (born at the 33 week of pregnancy) at the age of 8 weeks. An excess of the vitamin D dose by 15 times (15 000 IU/day instead of 1000 IU/day prescribed by the doctor) led to a concentration of 25(OH)D of 210 ng/ml and to a clinical picture of intoxication. During detoxification therapy, the 25(OH)D concentration decreased to the normal range in 4 weeks after vitamin D discontinuation. It is necessary to focus parental attention to the accuracy of adherence to the vitamin D regimen prescribed by the pediatrician. rd