STUDY AIM: The impact of iterative surgery in medullary thyroid carcinoma is still debated. The study aim was to evaluate long-term results following reoperation for residual or recurrent medullary thyroid carcinoma. PATIENTS AND METHOD: Among the 136 patients operated on in our centre for medullary thyroid carcinoma (MTC) between 1970 and 2000, 25 patients (10 men and 15 women) were reoperated on for locoregional residual or recurrent lesions. Their mean age was 46 years (range: 19-73 years). The MTC was sporadic in 21 patients and familial in 4: NEM 2A (n = 3), NEM 2B (n = 1). In 11 patients (44%) operated in another centre, the first procedure was a total thyroidectomy; in 2 patients (8%) a total thyroidectomy with central lymphadenectomy was performed, and in 12 patients (48%) a total thyroidectomy with central and jugulo-carotid lymphadenectomy. After the first operation, 6 patients (24%) were classified stage II, 15 (60%) stage III and 4 (16%) stage IV. Basal and post-stimulation calcitonin dosages were performed for all the patients before and after reoperation. RESULTS: Thirty three reoperations were performed. In 24 cases, the recurrence was located in the laterocervical site; in 5 cases, the lymph node involvement was both central and laterocervical, in 2 cases, there was a mediastinal involvement and in 2 cases a spinal involvement. After reoperation, the calcitonin rate became normal in 4 patients (16%); in the other 21 (84%), the calcitonin rate was still high. With a mean 110 month--follow-up (range: 320-12 months), 4 patients (16%) were alive without disease, 2 (8%) died of their disease, 19 (76%) were alive with their disease, five of them with hypercalcitonemia without detectable metastasis. In addition to patients having metastasis at the time of reoperation, seven developed metastases secondarily (liver, bone, lung). CONCLUSION: Biological cure of medullary thyroid carcinoma is rarely obtained with reoperation. Reoperations may reduce progression of the disease in selected patients. Complete removal of the lesions at the time of the first procedure must be the ideal treatment for medullary thyroid carcinoma.