Asthma is primarily an inflammatory disease and the bronchial airways have been shown to be particularly susceptible to oxidant-induced tissue damage. Oxidative stress can have many effects on airway function including airway smooth muscle contraction induction of airway hyper responsiveness mucous hypersecretion epithelial shedding and vascular exudation. Vitamin C is the most essential antioxidant within the lung lining fluid of the airways and is a protective factor against external oxidants such as cigarette smoke and environmental pollutants. Increased asthma could in part be caused by inadequate dietary vitamin C or other antioxidants or inflammatory generation of endogenous oxidants. Objective of the present study was finding the status of serum vitamin C in patients suffering from bronchial asthma.