Nucleotide sequences of exon 51, adjacent intron areas, and regulatory region of the α1 chain of type I collagen (COL1A1) gene were analyzed in 41 patients with osteogenesis imperfecta (OI) from 33 fam ilies and their 68 relatives residing at Bashkortostan Republic (BR). Six mutations (four nonsense mutations c.967G>T (p.Gly323X), c.1081C>T (p.Arg361X), c.1243C>T (p.Arg415X), and c.2869C>T (p.Gln957X)) in patients of the Russian origin and two frameshift mutations (c.579delT (p.Gly194ValfsX71), and c.2444delG (p.Gly815AlafsX293)) in patients with OI of Tatar ethnicity as well as 14 single nucleotide poly morphisms in the COL1A1 gene were revealed. Mutations c.967G>T (p.Gly323X) and three alterations in the nucleotide sequence c.544-24C>T, c.643-36delT, and c.957 + 10insA were described for the first time.