Objectives - Our aim was to investigate the diagnostic impact of skin biopsies in CADASIL patients. Materials and methods - Eight consenting CADASIL patients belonging to a German-Caucasian kindred were assessed clinically, genetically, by MRI and skin biopsy. Skin biopsy results were compared to 5 patients suffering from sporadic leucoencephalopathies (control group). Results - Six CADASIL patients presented with symptoms ranging from migraine to severe tetraparesis with dementia. Two clinically unaffected patients had abnormal MRIs. On MRI7 patients showed various degrees of leucoencephalopathy. One 22-year-old woman with migraine had a normal MRI. Granular, electron dense, osmiophilic material (GEM) was found in skin biopsies of all 8 patients including the 22-year-old woman with migraine and a normal MRI. As shown by genetic linkage analysis she was carrying the disease haplotype. GEM was not found in the control group. Conclusion - Our findings substantiate the impact of skin biopsies in defining the carrier status in CADASIL families.