Vasculitis refers to a heterogeneous group of disorders characterized by the inflammatory destruction of blood vessels. Inflamed blood vessels can become blocked, ruptured, or develop a thrombus and thus lose their ability to deliver oxygen and other nutrients to tissues and organs. Depending on the size, distribution, and severity of affected vessels, vasculitis can result in clinical syndromes that range in severity from a self-limited minor rash to a life-threatening multisystem disorder. 1. Because it often begins with nonspecific symptoms and signs and develops slowly over weeks or months, vasculitis is one of the great diagnostic challenges in all of medicine. However, physicians who know the general and specific clinical clues of vasculitis can often learn to suspect the presence of vasculitis at the patient's bedside. To establish the diagnosis of vasculitis, confirmation by laboratory tests is required, usually a biopsy of an involved artery but sometimes an angiogram or a serological test 4, 5. The demographic and epidemiological characteristics of vasculitic diseases vary considerably from country to country. This variation may reflect genetics, environmental differences, and the prevalence of other risk factors.7 Although some patients with vasculitis are seen by other specialists (dermatologists, pediatricians, internists), only patients seen and managed were recruited into our study. by a rheumatologist. Therefore, some forms of vasculitis (e.g. IgA vasculitis, cutaneous leukocytoclastic angiitis and Kawasaki disease) may be underreported. Vasculitis may occur as a primary process or may be secondary to another underlying disease. 4. We only studied patients with primary vasculitis; patients with secondary vasculitis were not included. ...... half of the article ......thematic vasculitis in children 17. Ninety percent of cases fall into the pediatric age group. There is a male predominance with reported male-to-female ratios of 1.2:1 to 1.8:1 18. IgA vasculitis in our study was as frequent as the ACR 8 study, but much less than in the Danish study. In our study, it was slightly more common in males (1.2:1). Cutaneous leukocytoclastic angiitis (hypersensitivity vasculitis) is a clinical term that generally refers to an immune complex-mediated vasculitis of the small vessels of the skin that spares the internal organs and usually follows drug exposures or infections 19. It was the second type of most common vasculitis in our study (8.2%). The frequency of cutaneous leukocytoclastic angiitis in the population of Denmark 10 is much higher than in the population of northeastern Iran (Table 2). We found a male:female ratio of 0.8 to 1 and the average age was 38 years.