Smoking is defined as inhalation of burned tobacco that widely affect people around the world with high mortality rate. Periodontal disease is a common inflammatory disease caused by the disruption in the balance between the microorganisms and the host defense mechanisms which leads to mobility and tooth loss. Smoking is known as a major risk factor of the periodontal disease. The purpose of this thesis is to accumulate of latest data about the role of smoking in serious systemic disease in general and the etiology and pathogenesis of periodontal disease in a practical manner.