Hereditary motor and sensory neuropathy (HMSN) is genetically heterogeneous disorder of peripheral nervous system. The frequency of the disease varies from 10 to 40 cases per 100000 in different populations (Skre, 1974). The HMSN frequency in Bashkortostan republic is 10,3:100000. The most frequent cause of the disease is 1,5 Mb duplication in chromosome 17p11.2-12, comprising peripheral myelin protein (PMP22). The mutation frequency varies in different populations. The examined group of patients consisted of 136 HMSN patients from 96 families, living in Bashkortostan. 60 patients analyzed (62,5%) were clinically diagnosed as HMSN type I, 9 patients (9,38%) - HMSN type II, 1 patient (1%) - HMSN type IV and 1 patients (1%) - HMSN type V. HMSN type confirmation was required in 25 families. Gene PMP22 duplication analysis was performed using PCR-analysis of micro- and minisatellite DNA-loci in all patients without differentiation diagnoses for HMSN types. Gene PMP22 duplication was revealed in 38 patients from 30 unrelated families. The duplication frequency in unrelated patients was 31,25% for all types of HMSN and 50,85% - for HMSN type I , that appeared to be lower than in Western Europe countries, where the duplication frequency is 75-80% (Latour et al., 2001). In one examined family PMP22 duplication and HMSN, caused by this mutation, was found only in one family member, so, the detected mutation appeared to be mutation de novo.