We examined for the presence of 17p11.2 deletion, by Southern blotting and fluorescent in situ hybridization, 3 cases with progressive sensory-motor polyneuropathy and diffuse tomaculous changes at sural nerve biopsy. We demonstrated in all the cases the 17p11.2 deletion, previously reported in hereditary neuropathy with pressure palsy, an inherited disorder of the peripheral nervous system with similar pathologic changes but a different clinical phenotype. The molecular study of the 17p11.2 region should be considered as a non invasive method for differential diagnosis in selected cases of progressive polyneuropathy.