Adenoid cystic carcinoma has a long natural history but frequently proves fatal. The present study describes 108 patients with an adenoid cystic carcinoma of the head and neck seen over a 30-year period. Analysis of the data utilized both univariate and multivariate methods. Forty per cent of patients had tumours arising from the oral cavity and half of these were in the hard palate; 29% occurred in the major salivary glands; 41% of tumours were locally advanced at presentation and 11% had lymph node metastases at this time. The histological pattern was solid in 25%, cribriform in 40% and tubular in 20%. In addition, 15% of patients had a polymorphous low-grade adenocarcinoma and these were analysed separately. Primary site recurrence was more common in the presence of locally advanced tumours at presentation (T3-4) (P = 0.0093). Only six patients had surgery with adjuvant radiotherapy. Six patients had no curative treatment, 21 had primary radiotherapy, 39 had local excision and 42 radical excision. The actuarial primary site recurrence rate was 100% at 30 years. The neck node recurrence rate was 23% at 15 years. Tumour specific survival was 40% at 20 years. Solid histology had a worse prognosis than other histological types (P = 0.0429) but those patients with polymorphous low-grade adenocarcinomas fared very well. Patients with tumours of the hard palate fared better than those patients with tumours at other sites (P = 0.0301). Early disease at the primary site (T1-2) was a good prognostic sign (P = 0.0013). Patients with neck node metastases at presentation tended to do badly (P = 0.009).