Background: Diagnosis of lung cancer is often delayed because most of the patients are asymptomatic during the primary cancer stages. Infrared spectroscopy is an improved technique compared with the others for identifying abnormal tissue types because of its spatial and spectral capabilities. Therefore, this study is taking an advanced advantage of the physical and optical properties of the attenuated total reflection Fourier-transform infrared system.Methods: The attenuated total reflection Fourier-transform infrared has been applied for cancer detection at infrared wavelengths that range from 4000-400 cm-1. This technique may be a beneficial diagnostic method because it uses the principles of physics, as optics and photonics with a specific wavelength region, which can make an immense difference.Results: The attenuated total reflection Fourier-transform infrared system spectra of normal lung tissue showed main peaks at 3321 and 1637 cm-1, which has been assigned to the OH and C=O function group of amide I and has intensities of approximately 61% (OH) and 76% (C=O). That intensity has been shown to decrease in the cancer tissue. A new peak at 1545 cm-1 appeared in the cancerous tissue, which could be an amide II.Conclusions: The identification of a biochemical component from either normal or cancerous lung tissue would help to evaluate malignant tissue. Thus, the obtained results indicated degradation of the biochemistry component (protein) of the tissue due to carcinogenic disease.