Background: The extent of effects of laser on bronchial tissue are still unknown, and there could be a possible hazard of bronchial wall perforation. Purpose: We investigated microscopic appearance, histologic changes, EBUS and OCT image of damaged mucosal lesions after laser irradiation. Method: The laser system has diode laser with 810nm wave length. The rabbit trachea (n=20) was used for laser irradiation(2.5 J/cm2, 5 J/cm2, 10 J/cm2, 15 J/cm2) aftr euthanasia. We built an 850 nm spectrometer-based OCT system with a full width at half maximum of 100 nm was used. EBUS with20-MHz frequency ultrasonic radial probe (UM-BS20-26R; Olympus) were utilized. Result: Microscopic appearance after a 2.5 J/cm2 application revealed whitening of the mucosa with a small, well-defined lesion (0.11 mm (0.05-0.20)), 5 J/cm2 with submucosal damage, some charring (0.20 mm (0.10-0.35)). 10-15 J/cm2 with deeper crater-shaped lesions with tracheal cartilage perforation, more profound charring (0.52 mm, 1.22 mm respectively). Examination of EBUS and OCT image showed crater-shaped appearance of the mucosal lesions containing varying quantities of coagulation necrosis after 2.5-5 J/cm2. However, after 10-15 J/cm2 applications, cartilage damage was already seen. Conculsion: There is the good correlation between the visibility of mucosal damage during laser treatment, the finding of optical coherent tomogram, and the ultimate histologic changes is of great practical value.