Background We designed allele-specific primers to amplify genomic DNA of patients with Charcot-Marie-Tooth 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP). Methods Genomic DNA analysis was performed on 40 unrelated CMT1A duplication patients, 25 unrelated HNPP deletion patients, and 50 unaffected control individuals. The CMT1A and HNPP patients had previously been identified with microsatellite mapping. Results Amplification products came to 3.6 kb in length from the normal proximal CMT1A repeated segment on chromosome 17p11.2 (proximal CMT1A-REP), 3.57 kb from the normal distal CMT1A repeated segment on chromosome 17p11.2 (distal CMT1A-REP), 3.6 kb from HNPP patients, and 3.58 kb from CMT1A patients. We could identify the mutations by means of agarose gel electrophoresis after polymerase chain reaction (PCR) amplification without restriction enzyme digestion from 33 of the 40 CMT1A and 19 of the 25 HNPP samples. Conclusion Stringently specific primers were used to overcome the problem of nonspecific amplification and provide a rapid, all-or-none PCR product and efficient screening test for CMT1A and HNPP.