Charcot-Marie-Tooth (CMT) is a common inherited peripheral neuropathy with a prevalence of 1 in 2,500. CMT has two distinct forms (CMT1 and CMT2) that can be identified electrophysiologically. A 1.5 Mb tandem microduplication including peripheral myelin protein 22 gene (PMP22) on chromosome 17p11.2-12 causes CMT1A. The increased gene dosage effect of PMP22 is thought to be responsible for the pathogenesis of CMT1A. In this study, 39 Turkish CMT1A patients and 60 unrelated control samples had been examined for the duplication using polymorphic short tandem repeat (STR) markers. Seven STR marker sites (AC005838-4A-, AC0013248-9A-, AC0013248-9B-, D17S2218, D17S2220, D17S2227, and D17S2229) on the duplicated region were amplified via polymerase chain reaction, electrophoresed through 8% polyacrilamide gel and evaluated for the duplication. The rate of duplication was 92.3' (36/39) in the patients whereas it was zero in the control samples. Allele distributions, number of alleles and heterozygosity values of more informative markers ( D17S2218, D17S2220, D17S2227, and D17S2229) were assessed. It is found that approximately 85% of duplications in Turkish CMT1A patients were depicted by using D17S2220 and D17S2229 markers together.