Total thyroidectomy has become the routine procedure for treatment of differentiated thyroid carcinoma. However, the necessity of unilateral or bilateral neck dissection is far less standardized. Our usual procedure has been to perform a routine neck dissection in T4 tumors and in all other tumor stages only in the presence of positive diagnostic or intraoperative findings. The results concerning regional tumor recurrence in cervical lymph nodes subsequent to thyroidectomy are studied and discussed. Between April 1986 and December 1992 a group of 252 patients were operated on for differentiated thyroid carcinoma (DTC) (176 papillary, 76 follicular). Postoperative treatment included radioiodine therapy as a rule in all patients more than stage T1, and follow-up encompassed thyroglobulin measurements, cervical ultrasonography, and radioiodine scintigraphy. After a mean follow-up of 6.9 years, 77 (31%) of the patients underwent reoperation because of regional tumor recurrence [46 of 176 (26%) papillary, 31 of 76 (41%) follicular]. In papillary thyroid cancer a significant difference could be demonstrated between patients with thyroidectomy only versus thyroidectomy plus neck dissection in all tumor stages (T2, 13 of 29 (45%) versus 1 of 34 (3%); T3, 10 of 13 (77%) versus 4 of 11 (36%); T4, 6 of 8 (75%) versus 6 of 18 (33%) (p < 0.0001). Similar results could be achieved for follicular thyroid cancer, showing statistical significance with regard to operative procedure (p < 0.009). Our experience demonstrates a positive correlation of regional tumor recurrence with increasing tumor stage for both histologic tumor types. The high rate of regional recurrence justifies a more radical approach, including neck dissection at the initial operation. The impact on survival, however, must be proved by further evaluation.