Aim: using PCR-RFLP to determine the VDR gene Foki polymorphism in children with UTI. Patients, materials and methods: the authors conducted a descriptive study on 36 children with UTI and 36 healthy children, the VDR gene Foki polymorphism of whom was determined by PCR-RFLP. Results and conclusions: PCR-RFLP was successfully conducted to determing the VDR gene Foki polymorphism. The frequencies of the FF, Ff and ff genotypes were respectively 0.25, 0.583 and 0.167 in the patient group. The frequency of ff genotype was higher in patients than in control, and also in upper UTI than in lower UTI, however these differences were not statistically significant.