Between 1940 and 1985, 24 cases of primary carcinoma of the trachea were registered at the London Regional Cancer Centre. The most common presenting symptoms were hoarseness, haemoptysis and cough. Twenty patients had epidermoid carcinoma and four had adenoid cystic carcinoma. Because of different clinical behaviours, the two histologies were separately analyzed. Of the 20 patients with epidermoid carcinoma, 19 received radiotherapy as primary treatment and one patient did not receive radiotherapy because of advanced disease. Radiation doses ranged from 4000 to 6000 cGy and most patients had megavoltage irradiation. Treatment result was disappointing. Only one patient remained disease-free at 15-month follow-up and all other patients had persistent or recurrent tracheal tumour. Median survival for all 20 patients was 5 months (range 1 to 19 months). Of the four patients with adenoid cystic carcinoma, two had primary surgery and postoperative radiotherapy and two had primary radiotherapy. Two patients died of disease, at 5 months and 8 years from diagnosis. Two surviving patients had 15-month follow-up: one had persistent disease and the other was free from recurrence. In this study, radiotherapy within the range of doses given was found to be an ineffective primary treatment for tracheal carcinoma.