INTRODUCTION: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetically determined and hereditary cerebral small vessel disease caused by mutations in the NOTCH3 gene. The onset is in the 3rd and 4th decade of life and is preceded by leukodegenerative changes, which are best visualized by magnetic resonance imaging (MRI). The prevalence of CADASIL is estimated at 2 to 5 people in 100,000. The clinical picture is heterogenous. The main clinical features include recurrent subcortical ischemic events, mood disturbances, progressive cognitive impairment and migraines with aura. Despite the growing recognition of CADASIL, this disease is still a diagnostic challenge. CASE REPORT: A 60-year-old man was referred to the genetic clinic for suspected CADASIL. The initial clinical symptoms probably occurred at the age of 40 in the form of radiological changes. The MRI performed then revealed periventricular zones of a T2 hyperintense signal. Based on follow-up MRIs, the patient was diagnosed with multiple sclerosis or acute disseminated encephalomyelitis. At the age of 58, following a seizure attack he was admitted to hospital and a performed MRI that revealed periventricular white matter degeneration and lacunes. CADASIL was suspected to be the cause. The diagnosis was confirmed by molecular testing. A pathogenic variant NM_000435: c.268C > T (p.Arg90Cys) was detected. CONCLUSIONS: It is relevant to pay attention to radiological findings and family history in the diagnostic process of a patient presenting symptoms which may suggest CADASIL to differentiate this genetic condition from demyelinating diseases.