Squamous-cell carcinomas are the most frequent skin cancer after the basal-cell carcinomas. They occur in precursor lesions (dysplasia, actinic keratoses, Bowen's disease). They are mainly present in sun-exposed areas (face, hands). It is important to detect and treat them early. Surgical treatment is easy at an early stage. At a later stage their prognosis is poorer because the squamous cell carcinomas tend to invade locoregional tissue and metastase. Their prevention remains the most important thing by using a photoprotection and treating actinic keratoses.