Abstract The role of thyroid ablation following thyroidectomy for invasive follicular cancer remains controversial. The use of iodine 131 ( 131I) ablation as adjuvant therapy may facilitate follow-up of patients in whom serum thyroglobulin levels and 131I total body scans are used to detect metastatic disease. It is uncertain if 131I ablation improves survival of patients with follicular thyroid cancer. Thus, the purpose of this study was to determine if survival is enhanced following ablation, with particular reference to those patients with minimally invasive cancer. Between the years 1955 to 1988, 142 patients with invasive thyroid follicular cancer were treated at the British Columbia Cancer Agency, of whom 71 had minimal invasion and no extrathyroidal extension of tumor. In this group of patients, 46 underwent hormone suppression only, 17 had ablation, and 8 had neither. The average follow-up was 9 years and extended beyond 15 years in many patients. Data were entered in a mainframe computer, and Kaplan-Meier survival analysis was used, comparing crude survival, disease-specific survival, and disease-free survival. There was no significant difference between groups. In patients with follicular thyroid cancer and capsular invasion only, 131I ablation does not improve survival compared with patients treated with thyroid hormone suppression only.