Photoradiation (photodynamic) therapy of endobronchial primary and metastatic lung cancers uniformly results in a complete response--that is, the opening up of totally or partially obstructed bronchi to their walls. The method, employing hematoporphyrin derivative and red laser light from an argon-pumped dye laser, is safe, efficient, and effective. The safety and lack on any complications rest upon the use of light-diffusing cylinder tips, and upon clean-up bronchoscopy to remove tumor debris promptly. The trachea and main and lobar bronchi, as well as segmental and subsegmental bronchi, can be entirely freed of tumor and completely opened up.