The effects of endoscopic Nd:YAG laser surgery were studied in 36 patients with unresectable advanced primary and metastatic malignancies in the trachea with special reference to the factors influencing long-term survival. Overall effectiveness of YAG laser treatment was demonstrated in 34 of the 36 patients (94 per cent), while the overall 1, 3 and 5 year survival rates after the first laser treatment were 25 per cent, 13 per cent and 13 per cent, respectively. Neither histologic type nor the severity of clinical symptoms before laser treatment showed any significant influence on the survival curves, however, endoscopic findings of stenosis, the effect of laser treatment and irradiated longitudinal length were all significantly correlated with the survival curves. In other words, endoscopically protruding type tumors with a longitudinal length of irradiation of 3.0 cm or less, and good responses not only to laser treatment but also to other combined modalities are favorable factors for achieving long-term survival in patients with tracheobronchial malignancies undergoing endoscopic Nd:YAG laser treatment. Endoscopic Nd:YAG laser surgery is considered to be a promising part of the multi-modality treatment for unresectable advanced primary and metastatic malignancies of the trachea.