Vasculitis refers to a heterogeneous group of disorders characterized by inflammatory destruction of blood vessels. Inflamed blood vessels are likely to become blocked, rupture, 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 the affected vessels, vasculitis can result in clinical syndromes that range in severity from a self-limiting minor rash to a life-threatening multisystem disorder. 1. Because it often begins with nonspecific symptoms and signs and progresses slowly over weeks or months, vasculitis constitutes one of the great diagnostic challenges in all of medicine. Yet, physicians who are familiar with the general and specific clinical clues of vasculitis can often learn to suspect the presence of vasculitis at the bedside. Establishing the diagnosis of vasculitis requires confirmation by laboratory tests, usually a biopsy of an affected artery but sometimes angiography or serological testing 4, 5. The demographic and epidemiological characteristics of vasculitic disorders vary considerably by geography. 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 charge by a rheumatologist were recruited in our study. . Thus, some forms of vasculitis (e.g., IgA vasculitis, cutaneous leukocytoclastic angiitis, and Kawasaki disease) may be underestimated. Vasculitis can occur as a primary process or secondary to another underlying disease. 4. We only studied patients with primary vasculitis; patients with secondary vasculitis were not included. ...... middle of article ...... temic vasculitis in children 17. Ninety percent of cases are in the pediatric age group. There is a male predominance with male/female ratios of 1.2:1 to 1.8:118. IgA vasculitis in our study was as frequent as in the ACR 8 study, but much lower than in the Danish study. In our study, it was slightly more common in men (1.2:1). Cutaneous leukocytoclastic angiitis (hypersensitivity vasculitis) is a clinical term that generally refers to vasculitis of small vessels of the skin mediated by an immune complex that spares internal organs and usually follows drug exposures or infections 19. This was the second most common type of 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 to female ratio of 0.8 to 1 and the average age was 38 years old..