Mess removal, electrocoagulation, cryosurgery are conventional methods in the treatment of various oral mucosal diseases. However, there are several problems or complication during or after surgery using conventional tools. Recently, LASER gradually become useful tool in the surgery of oral mucosal diseases. Of the LASER, carbon dioxide-mediated LASER is widely used one. Carbon dioxide LASER has many advantages such as good bleeding control, decreased damage to adjacent tissue, decreased pain and swelling, reduced scar formation, even bacteriocidal effects. In this reports, the author describe pros and cons of LASER, especially focused on carbon dioxide, and shed light on the field of LASER application in treatment of various oral mucosal diseases.