Between August 1985 and September 1989, 62 patients with medically inoperable or surgically unresectable, non-small cell lung cancer were treated with both external beam radiotherapy and high dose rate bronchial brachytherapy. Treatment consisted of external beam radiotherapy (5000-6000 cGy in 5-6 1/2 weeks) and weekly high dose rate bronchial brachytherapy (three to five fractions, 500 cGy at 1 cm from the source) delivered either concurrently or sequentially. Median survival for all patients was 13 months (m). Stage I and Stage IIIA-B patients had median survivals of 20 m and 10 m, respectively. Patients without nodal disease (No) had a significantly longer median survival compared to patients with regional node metastases (N1-3), 17 m versus 9 m. A total of 54 patients were evaluable for local tumor control analysis. Local tumor control was achieved in six of eight patients who had a normal pre-treatment radiograph. Patients with measurable tumor on the pre-treatment radiograph and negative regional nodes had local tumor control in eight of twenty-two (36%) cases. In patients with regional lymphadenopathy, loco-regional tumor control was achieved in four of eight cases. Additionally, there were sixteen patients with non-measurable tumor due to associated effusion, atelectasis and/or infiltrate. Four of these (25%) were considered to have local tumor control. Of 60 evaluable patients, there were nine occurrences of fatal hemorrhage, one of whom was disease-free (NED) at autopsy. The remaining eight patients had either clinical or pathological evidence of recurrent or persistent tumor. Patients who had follow up bronchoscopies were found to have varying degrees of concentric narrowing in the treated areas. One such patient had total lung collapse with no evidence of tumor. While this form of treatment may yield high local control rates in earlier stages, this study suggests the potential risk of fatal complication. Additional studies are warranted to further investigate the use of this modality in the treatment of lung cancer.