Treatment outcome was retrospectively assessed in 106 patients with squamous cell carcinoma of the oral tongue registered in the population-based Manitoba Cancer Registry between January 1979 and December 1992. Twenty-six percent were diagnosed with stage I lesions, while 33%, 16%, and 24% were stage II, III, and IV, respectively. Most patients with stage I and II disease were treated with either surgery alone (57%) or in combination with radiotherapy (29%). Advanced lesions were generally treated with radiotherapy alone (37%) or in combination with surgery (35%). Actuarial survival at 5 years was 44% for all patients, and 64%, 46%, 42%, and 16% for stages I to IV, respectively. Over 90% of the 35 treatment failures occurred within 24 months. The initial sites of recurrence were the neck in 22 patients, the primary site in 16 patients, and distant metastases in 5 patients. At the time of death, disease was present above the clavicles in 62%, and metastases were identified in 22%. Locoregional control remains a significant problem in oral cancer. Elective treatment of the neck, resection of the primary with negative surgical margins, and the use of combined modality treatment in advanced stages of disease may help reduce treatment failure.