Spontaneous cerebral artery dissection is a common cause of ischemic stroke in young adults and children. Dissection is often related to arterial wall weakness the cause of which is unknown. An aim of the present paper was to carry out an electron microscopic study of skin arteries and arterioles in patients with ischemic stroke caused by cerebral artery dissection. Skin biopsy samples from 3 patients (2 men and one women, 15, 25 and 43 years of age, respectively) were studied. Electron microscopy revealed changes of endothelial, smooth muscle cells and fibroblasts in the skin microvessels. These changes included the decrease in the number of mitochondria and their alterations (vacuolization, destruction of the cristae, the presence of the needle-shaped crystals and crystal-like inclusions) and swelling of the endoplasmic reticulum. Some of these changes were characteristic of mitochondrial diseases. The changes in the extracellular matrix (thickening of the subendothelial layer and deposition of microcalcificats) were also detected. It is assumed that the mitochondrial cytopathy found in the skin microvessels may be also present in large cerebral arteries. This could underlie dysplastic changes in the cerebral artery wall and predispose to its dissection.