Myringotomy with insertion of ventilation tube is one of the most common surgical procedure in otolaryngology. However, several problems including early extrusion of the tube, permanent perforation and tympanosclerosis have been left unsolved. To solve the problems, we investigate the structural changes after laser myringostomy that could be applied on the tympanic membrane and might be an effective myringostomy procedure. Albino guinea pig weighing 250-300gm and having normal Preyer’s reflex and tympanic membrane was used. The tympanic membrane was exposed and laser myringostomy was performed by using argon laser. The power applied was 1 or 2 want, and irradiation time was 0.5 or 1 sec and spot size was 200μm. The guinea pigs were sacrificed and fixed, and processed for an observation of scanning electron microscope. One day after laser myringostomy, circular demarcation line was clearly recognized at some distance from the laser perforation, and translucent zone had developed around the laser perforation. Four day after laser myringostomy, the epithelial cells began to migrate toward the stoma. The stoma was partially covered 6 days and completely closed within 12 days. Clinically, laser myringostomy dose not need to operate microinstruments such as myrigotomy knife and alligator in anatomical complex and narrow external auditory canal and could be performed within so brief time shorter than one second without damage to surrounding tissue. It was thought that myringostomy using Argon-Laser might be beneficially utilized in serious otitis media requiring short-termed ventilation of middle ear cavity, or in acute otitis media requiring myringotomy.