Actinic cheilitis is a potentially malignant disorder that mostly affects the vermilion border of the lower lip and can lead to squamous cell carcinoma. Because of its heterogeneous clinical aspect, it is difficult to indicate representative biopsy area. Late diagnosis is a limiting factor of therapeutic possibilities available to treat oral cancer. The diagnosis of actinic cheilitis is mainly based on clinical and histopathological analysis and it is a time consuming procedure to get the results. Information about the organization and chemical composition of the tissues can be obtained using fluorescence lifetime spectroscopy techniques without the need for biopsy. The main targeted fluorophores are NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide), which have free and bound states, each one with different average lifetimes. The average lifetimes for free and bound NADH and FAD change according to tissue metabolic alterations and allow a quick and non-invasive clinical investigation of injuries and to help clinicians with the early diagnosis of actinic cheilitis. This study aims to evaluate the fluorescence lifetime parameters at the discrimination of three degrees of epithelial dysplasia, the most important predictor of malignant development, described in up to 100% of actinic cheilitis cases.