Smoking can increase oxidative stress and thereby change the antioxidant defense system in the body. Supplementation of antioxidant vitamins might improve antioxidant status in the body. The purpose of this study was to evaluate the effectiveness of vitamin C supplementation and smoking cessation education on changes of antioxidant status and psychosocial factors related to smoking. To obtain above purposes, we investigated the effectiveness of intervention for male adolescent smokers were evalnate by assessing changes in dietary intakes, plasma antioxidant vitamin concentration, and psychosocial factors related to smoking after program completion. Subjects, male adolescent smokers, were assigned into four groups : Control group(19 students), Educ. group(19 students), Vit. C supple. group(19 students), and Educ.+Vit. C suppl. group(19 students). The Educ. group and Educ.+Vit. C suppl. group received nutrition and smoking cessation education once a week for 5 weeks. Vit. C suppl. group and Educ.+Vit. C suppl. group received 500 mg per day of ascorbic acid for 35 days. All data were collected before and after intervention. Vit. B$_2$and Vit. C intakes of all groups were increased, but the only Ca intake was increased in the Educ. group. Plasma Vit. C concentration and Ratio(plasma Vit. C/Vit. C intakes) were increased in the Vit. C suppl. group and Educ.+Vit. C suppl. group, and the Vit. C deficiency status of these groups(Vit. C suppl. group and Educ.+Vit. C suppl. group) disappeared. Showing the effects of Vit. C supplementation, plasma $alpha$-tocopherol was increased in the Educ. and Educ.+Vit. C suppl. group, and especially high increases were seen in the Educ.+Vit. C suppl. group. Psychosocial factors related to smoking changed after the education a little. This intervention program had an impact on nutrition intakes, plasma antioxidant vitamins, and some beliefs related to smoking in male adolescent students. Various programs of nutrition and smoking cessation education and vitamin supplementation for quitting smoking must be implemented for adolescent smokers, and further studies are needed regarding sorts and amount of antioxidant nutrients and supplementation periods.