This retrospective clinical study was designed to analyze the impact of the initial surgical procedure on the survival of 1000 patients with differentiated thyroid cancer of follicular cell origin who had a thyroid operation and were followed for the 30 years between 1968 and 1998 (median 14 years) in an iodine-deficient region where goiter is endemic. There were 753 women and 247 men with a mean age of 42.8 +/- 6.7 years (range 17-86 years). Patients were divided into three groups. All patients had undergone thyroxine treatment and thyroid-stimulating hormone (TSH) suppression, and most had had iodine-131 treatment postoperatively. Group A consisted of 336 patients with differentiated thyroid cancer (DTC) who were treated with bilateral subtotal thyroidectomy in our institution or elsewhere. Group B consisted of 158 patients with DTC who were treated initially with unilateral total lobectomy and contralateral subtotal lobectomy in our institution or elsewhere and underwent reoperation in our department. Group C consisted of 506 patients with DTC who were treated initially with total or near-total thyroidectomy in our department. Kaplan-Meyer survival analysis was used. Recurrence was seen in 23% and death in 8% of the patients. The 20-year survival rates were 76%, 85%, and 92% for groups A, B, and C, respectively. The survival difference among the patients of group A and groups B and C was found to be statistically different (p < 0.001). Long-term survival of patients with differentiated thyroid cancer living in endemic areas for goiter can be influenced by the initial surgical treatment. Patients treated initially with total or near-total thyroidectomy appear to have a better prognosis.