Head and Neck cancer is one of the most common cancers in the world, nearly two-thirds of which occur in the developing countries. Oral cancer detection at a late stage leads to high mortality and morbidity. The time of diagnosis influences the treatment and survival rate. It is often difficult to distinguish neoplastic and premalignant disorders with standard white light illumination. Biopsy of the lesion with histopathological examination will always be the gold standard for diagnosis of oral cancer, which, however, has some limitations. It is time consuming, expensive, invasive, and needs a trained health care provider. Optical spectroscopy has the potential to detect malignant lesions before they become macroscopically visible, by probing tissue biochemistry and morphology in vivo in real time. During the development of premalignant and malignant changes, epithelial cells undergo a transformation that results in modified rates of metabolic activity, cellular proliferation, and/or death. Autofluorescence and diffuse reflectance spectroscopy have been studied as non-invasive in vivo tools for the detection of malignant and potentially malignant tissue alterations. Fast and non-invasive, diagnostic techniques based on fluorescence spectroscopy have the potential to link the biochemical and morphological properties of tissues to individual patient care. The use of endogenous and exogenous fluorescent markers, with tumour-localizing properties, for the clinical detection of early cancer in vivo has been investigated by several studies. Autofluorescence of tissues under excitation with light is produced by several endogenous fluorophores. These include fluorophores from tissue matrix molecules and intracellular molecules like collagen, elastin, keratin, FAD, and NADH. The presence of disease changes the concentration of these fluorophores, which makes autofluorescence spectroscopy sensitive to tissue alterations. Diffuse reflectance is the result of single and multiple backscattering of the white excitation light. Early diagnosis is made possible with Raman spectroscopy systems based on the principle that optical spectrum acquired from a tissue and biological fluids from blood, urine, and saliva will contain information about its histological and biochemical characteristics. This poster highlights our three research studies on optical diagnostic aids; autofluorescence, diffuse reflectance spectroscopy and Raman spectroscopy in differentiating normal, premalignant, and malignant conditions. Schlagwörter: Oral cancer, optical diagnosis, early diagnosis, potentially malignant disorders