Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary cerebral microangiopathy linked to mutations in the Notch3 gene. The cerebral impairments of CADASIL are well-known, but peripheral nervous impairments such as polyneuropathy are less clear. Recently, peripheral neuropathy was proposed as one of the CADASIL phenotypes. We investigated peripheral nerve involvement in CADASIL patients. Forty-three CADASIL patients with confirmed Notch3 gene mutations underwent a nerve conduction studies using a conventional surface technique in 86 upper and lower extremities. Nerve conduction abnormalities were apparent in seven of the 43 patients. Of the seven patients, four displayed nerve entrapment syndromes (carpal tunnel syndrome, n = 3; ulnar neuropathy, n = 1), and three displayed sensorimotor polyneuropathy. Of the latter three, two patients had diabetes mellitus. We suggest that peripheral neuropathy may not be part of the CASASIL phenotype. However, genotype-phenotype heterogeneity can not be excluded.