High levels of free radicals in tobacco smoke are thought to be responsible for decreased levels of serum ascorbic acid in smokers and adults exposed to environmental tobacco smoke. The association of environmental tobacco smoke to serum ascorbic acid in children is unknown. One hundred forty children were "clected, 70 children were exposed to environmental tobacco smoke at home by {hl'ir parents (exposed group 1) and 70 children were not exposed to l'mironmcntal tobacco smoke at home (control group 2). The serum cotinine levels and serum ascorbic acid level were measured in the two groups of children. The serum cotinine levels were significantly increased in exposed group (p< 0.05) and ,,:ere positively correlated with the number of cigarette smoked by the household contacts (r 0.54, p < 0.05). The serum vitamin C level was significantly decreased in the cxposed group (p< 0.05) and was positively correlated with the serum cotinine k cI (r 0.63, p< 0.05). Thus we conclude that exposure of children to cmironmcntal tobacco smoke leads to significant decrease in serum ascorbic acid In d. Thcre fore, this study further high lights the potential dangers of l'mironmental tobacco smoke to children. Keywords: Vit C, Tobacco