The vibrational spectroscopy is a tool for obtaining data at the molecular level, and for this reason has been studied as a method to facilitate the diagnosis and monitoring of disease. The infrared absorption spectroscopy by Fourier Transform has achieved promising results, mainly in studies related to diagnosis of cancerous tissue, such as breast cancer and prostate cancer, because it is a minimally invasive technique for the patient and fast and high precision. Furthermore, the studies regarding the biopsy, liquid, using bodily biofluids called net biopsy, gaining space in the medical and scientific community, due to the availability of samples, ease of storage and easy reproducibility of tests, in addition to the collection of samples to be minimally invasive. The objective of this study to analyze salivas of patients in two groups, one group of patients without any type of cancer, and another group of patients with cancer in particular cancer of the oral cavity, being these groups people smokers, ex smokers and people who have never smoked, by infrared absorption spectroscopy by Fourier transformed in order to know if it would be possible to discriminate groups by their spectral differences, using it as a diagnostic tool, by comparing the samples also prepared and analyzed It was developed a methodology for the preparation of the saliva samples in an environment of high relative humidity <80% for homogeneous drying of components for use in the ftir. The results of spectral analysis, as well as the analysis of cluster (HCA) showed the separation of the study groups, the control group and the group with the pathology, showing that the effect of the methodology of preparation and usedu patterns on the equipment, the FTIR proved to be efficient for diagnosis of oral cancer.