At least 5 different genes of autosomal dominant spinocerebellar ataxias (SCA) were revealed recently. Their discovery permitted to elaborate the most perfect classification of this heterogeneous group of diseases. In two forms of ataxias (SCA1 and SCA3) the mutations consist in the expansion of CAG-trinucleotides repetitions. The Russian population of patients with dominant SCA (13 families) was examined for the first time in terms of the evaluation of mutant gene carriers of SCA1 and SCA3. SCA1 was diagnosed in 5 families on the molecular level. The cerebellar ataxia, dysarthria as well as pyramidal symptoms comprised the basis of SCA1 clinical pattern. There were no SCA3 cases at DNA-testing. The perspectives of DNA-diagnosis of inherited ataxias were considered.