Twenty subjects participated in a pilot study to investigate the association between tobacco smoke intake and several biomarkers. Study endpoints included biomarkers for nicotine, benzene, acrolein, tobacco-specific nitrosamines (TSNA), polycyclic aromatic hydrocarbons (PAH), oxidative stress, and carbonyl protein adducts. The experimental design consisted of 10 smokers and 10 nonsmokers. Biomarkers that were significantly different (p<0.05) between smokers and nonsmokers were as follows: urinary nicotine and 5 nicotine metabolites, free and total NNAL (TSNA), urinary 1-hydroxypyrene (PAH), urinary S-phenylmercapturic acid (benzene), urinary hydroxypropylmercapturic acid (acrolein), and carbonyl adducts as determined in mouthwash samples. Biomarkers that were not significantly different (p>0.05) between smokers and nonsmokers were as follows: urinary 8-OHdG (oxidative stress), 8-OHdG as determined in mouthwash samples (oxidative stress), urinary t,t'-muconic acid (benzene), and urinary 8-iso PGF2 a isoprostane (oxidative stress). The results of this study indicate that some biomarkers are more sensitive than others in differentiating smokers and nonsmokers. Of the biomarkers not significantly different in this pilot study, some of them may differ if studied in a greater number of subjects or in a different study design.