To estimate survival of patients with loco-regional recurrences (LRRs) of differentiated thyroid carcinomas (DTCs) and to identify factors associated with survival after LRRs, we analyzed retrospective data of the 172 patients treated and followed up in our institution from 1958 to 2000 who had developed LRRs (6% of DTC patients). Ultrasound, when used, picked up 95% of the recurrences. Survival was estimated with the method of Kaplan-Meier, and associated prognostic features were studied in univariate and multivariate Cox model-based analyses. Cumulated survival rates 10 yr after LRRs were 49.1, 89.3, and 32.1% for all patients, patients aged less than 45 yr, and older patients, respectively. Multivariate analysis identified three features related to initial tumor (age >/= 45 yr, follicular histology, presence of thyroid capsular effraction), the absence of radioiodine ablation of thyroid remnants after initial surgery (10% of patients did not receive radioiodine), the presence of distant metastases before LRR diagnosis, and two features related to the LRRs (no radioiodine uptake and thyroid bed location) as significantly associated with a reduced survival. Our results underline the seriousness of LRRs of DTCs and could be used to identify patients who should benefit from a closer follow-up and especially reactive therapeutic intervention.