The goal of the study was to evaluate intragenic polymorphic sites in COL1A1 and COL1A2 loci. For COL1A1 the following intragenic markers were used: PCR-RFLP (COL1A1), G/A polymorphism in exon 45 of COL1A1 and C/T polymorphism in +88 position of COL1A1 non-translatable 3' end. For COL1A2 PCR-VNTR was analyzed. 17 families were examined (6 of the 'simplex' type and 11 of the 'multiple' type). In 8 out of 11 'multiplex' families the segregation of the markers revealed correlation with OI, whereas the other 3 were non-informative. The method was not useful in 'simplex' families.