BACKGROUND: Nicotine metabolite ratio (NMR) can be used to predict total nicotine clearance. However, it is unknown whether NMR could be used as a marker of lung cancer risk. OBJECTIVE: To evaluate the blood metabolites of nicotine relating to the risk of developing lung cancer and investigate the combined effects of NMR and cigarette per day on the risk of lung cancer. METHODS: Among the 1,054 eligible subjects from the Korean Cancer Prevention Study-II biobank cohort, those with cotinine values below 0 ng/ml were excluded. Slow and fast metabolizer groups were defined using the median value of the NMR, calculated with the control group data, as the cut-point. RESULTS: The multivariable Cox proportional hazard models demonstrated that, the fast metabolizer group had a significantly higher risk of lung cancer than the slow metabolizer group (Adjusted HR: 2.02, 95% CI: 1.32–3.10). Fast metabolizers who smoked more than 15 cigarettes per day had an even higher risk of lung cancer (Adjusted HR: 3.51, 95% CI: 1.96–6.29) than the slow metabolizers who smoked less than 15 cigarettes per day. CONCLUSIONS: In summary, the NMR may be an effective marker for estimating tobacco-related disease risks such as lung cancer.