The enzyme 8-oxoguanine glycosylase 1 (OGG1) repairs oxidatively damaged DNA and a polymorphism in the OGG1 gene (Ser326Cys) has been associated with lung cancer. We examined associations between the polymorphism and intake of fruits and vegetables and smoking in the development of lung cancer, by genotyping blood samples from 431 lung cancer cases and 796 comparison persons, which were identified within a prospective cohort on 57,000 cohort members. We found no overall association between the OGG1 polymorphism and lung cancer. There was a statistically significant interaction between the polymorphism and dietary intake of vegetables, with a 54% decrease in lung cancer risk per 50% increase in vegetable intake among homozygous Cys326Cys carriers and no decrease in risk among carriers of Ser326Ser or Ser326Cys. The same tendency was seen in relation to intake of fruit. There were no statistically significant interactions between the OGG1 polymorphism and smoking.