Aplastic anemia is characterized by pancytopenia with hypocellular bone marrow. Fifty percent of the cases are idiopathic and the rest are caused by various agents including drugs, chemicals, radiation and viruses. It is difficult to link specific etiologic agents, especially chemicals to the development of aplastic anemia because multiple or unknown exposures may be involved in. Benzene, a common industrial chemical and a component of gasoline, may lead progressively to pancytopenia, aplastic anemia and leukemia when exposed. A petrochemical worker with aplastic anemia was referred to our hospital to evaluate a relationship between the job history and the disease. He worked in the petrochemical plant for .21 years and was exposed to low-level benzene. There was not any other etiologic agent except benzene and this is the case report of aplastic anemia which possibly due to benzene exposure.