Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited vascular disorder caused by Notch3 gene mutations. The main histopathological hallmark is granular osmiophilic material (GOM) deposited in the close vicinity of vascular smooth muscle cells (VSMCs). The authors report the first 7 ultrastructurally and genetically confirmed cases of CADASIL in Serbia. Samples of skin and sural nerve were investigated by transmission electron microscopy. GOM deposits were observed around degenerated VSMCs in all the skin biopsies examined. Sural nerve biopsies revealed severe alterations of nerve fibers, endoneurial blood vessels with GOM deposits, endoneurial fibroblasts, and perineurial myofibroblasts. Total genomic DNA was extracted from peripheral blood leukocytes, and exons 2-6 of the Notch3 gene were amplified by PCR and subsequently sequenced. Four different mutations in exons 2 (Cys65Tyr), 3 (Gly89Cys and Arg90Cys), and 6 (Ala319Cys), which determine the CADASIL disease, were detected among all described patients. A novel missense mutation Gly89Cys involving exon 3 was detected. Due to the difficulties in the determination of the Notch3 mutations, these data suggest that electron microscopic analysis for GOMs in dermal vessel wall provides a rapid and reliable screening method for this disease.