Three patients with squamous cell carcinoma on the lower lip who were in mental hospital for a long time were reported. They had no history of taking a lot of sunshine because they had been in the hospital for 25 or 40 years. All of them were smokers but not so heavy, and had histories of the burn on the lower lip, because they usually smoke until the end of tabacco for the restriction to the number of it a day. They had cancer lesions at the site on which they always put the tabacco. For these reasons we suspect the inducer of these carcinoma is the burn scar not sunshine. And had much trouble in the treatment of these patients for their mental disease. We must plan operations without post-operation rest because of their disturbance after awakening of anethesia, and need much help of psychiatrists.