Carcinoma of the submandibular gland is a rare diagnosis, accounting for less than 2% of cases of salivary gland tumours. We have examined the treatment and outcome of a total of 30 patients treated with radiotherapy at the Christie Hospital, Manchester between 1980 and 1993. In most cases this followed radical surgery, though 12 patients were referred following either incomplete excision or biopsy only. Adenoid-cystic histology accounted for 19 cases (63%). Standard radiotherapy was delivered using a beam directed technique to treat the whole submandibular compartment. Doses prescribed were most commonly from 50 to 55 Gy in 16 fractions over three weeks. Cancer specific survival was 79% and 57% at 5 and 10 yr respectively, the continued fall at 10 yr reflected late recurrence seen in patients with adenoid-cystic histology. Local control was 85% and 73%, respectively. Nine of twelve patients with incomplete excision or biopsy only had local control with radiotherapy. Six patients developed lung metastases, all of whom had adenoid-cystic histology. Radiotherapy was well-tolerated acutely, and only one patient experienced osteoradionecrosis requiring surgical intervention. The incidence of adenoid-cystic carcinoma is higher in the submandibular than the parotid gland. This typically results in late recurrence, and a high incidence of lung metastases and this was confirmed in our study. However, overall survival was very similar to that of parotid carcinoma.