Introduction: In recent years, the number of surgical procedures involving the thyroid gland has increased worldwide; however, no increase in mortality rate has been observed. The Fourier Transform Infrared (FTIR) spectroscopy technique presents evidence in the characterization of multiple tissues, such as the thyroid gland, with the advantage of being rapid and preserving the tissue analyzed. Objectives: Characterize both healthy and pathological thyroid tissues by FTIR spectroscopy. Methods: Patients were selected at the Head and