OBJECTIVE To detect the duplication or deletion of peripheral myelin protein 22(PMP22) gene in Chinese patients with Charcot-Marie-Tooth disease(CMT) or hereditary neuropathy with liability to pressure palsies(HNPP) using real-time quantitative polymerase chain reaction. METHODS Duplications or deletions of PMP22 gene were detected in 113 CMT cases, 4 HNPP cases and 50 normal controls by using real-time quantitative PCR. RESULTS Thirty-six of 113 CMT cases had the PMP22 duplication, 4 HNPP cases had the PMP22 deletion. No duplication or deletion was found in 50 normal controls. CONCLUSION The PMP22 duplication rate in Chinese patients with CMT is 31.9%(36/113). PMP22 deletion is the common cause of HNPP.