Out of 201 patients with roentogenographically occult bronchogenic squamous cell carcinoma, 165 lesions underwent surgical operations, while 41 lesions underwent non-invasive therapy. The 5-year survival rate including all causes of death, was significantly higher in the surgical operation group than that in the non-invasive therapy group (83% vs 43%). Among 14 cases who received Nd-YAG laser treatment, one case died but 4 cases are alive bearing cancer. Since time span of follow-up period is short, it is hard to say that the prognosis of the Nd-YAG laser therapy in fair. Nd-YAG laser treatments were effective for cancers which did not invade beyond bronchial cartilage. From the bronchoscopic examinations and studies with resected lungs, we suggest that Nd-YAG laser treatments may be effective when cancer is extended within 10 mm wide and has only a slight findings in bronchoscopy.