3-Methylcholanthrene (MCA) is a polycyclic aromatic hydrocarbon and potent carcinogenic agent that is often used in experimental cancer studies. Butylated hydroxytoluene (BHT) has been widely used for many years as an antioxidant to preserve and stabilize the freshness, nutritional value, flavor, and color of foods. The aim of the present study was to investigate the role of the application of MCA and BHT in the development of lung cancer, and to detect any mutation in the Ki-ras gene exon 2. Rats were killed by cervical dislocation 26 weeks after the last BHT injection and lung tissues were surgically removed. Lung tissues of the control and experiment rat groups were examined for point mutations in the exon 2 of the Ki-ras by PCR based SSCP analysis. No point mutation was observed in the Ki-ras gene exon 2.