The role of surgery in the management of patients with primary lymphoma of the thyroid gland has been addressed after review of 61 patients treated at Princess Margaret Hospital between 1958 and August 1982, 46 of whom had clinical stage I and II disease confined to the thyroid gland or lymph nodes or both above the diaphragm. Postoperative radiation therapy was used in 34 patients, radiation therapy and chemotherapy in 11 patients, and chemotherapy alone in 1 patient. Analysis of disease progression, local relapse, and distant disease recurrence indicated that postoperative residual disease bulk predicted strongly for both local and distant disease progression. Overall cause-specific survival was 59% at 5 years, with a relapse-free rate of 46% at 5 years. Of those with less than 2.5 cm of residual disease after surgery, 80% achieved lifelong local disease control compared with 40% for those with residual disease in excess of 2.5 cm after surgery. Distant relapse rates were 7% and 23% for those with less than 2.5 cm and greater than 2.5 cm after surgery, respectively. The long-term survival rate for those with disease progression during this period was approximately 10%, with a median survival expectancy of 18 months. It is suggested that those patients without an antecedent cytologically based diagnosis of lymphoma undergo biopsy and removal of operable tumor without compromise of parathyroid glands, recurrent laryngeal nerves, or appearance. Those patients with an existing cytologic diagnosis of lymphoma and bulky and/or inoperable tumor may be more effectively managed with a combined chemotherapy-radiation therapy program.