Thyroid microcarcinoma is a malignant thyroid tumor with potential multifocality and a maximum of 1 cm of diameter. This carcinoma has been discovered more frequently like incidentaloma.To appraise the incidence of MCT in the benign thyroid diseases and the advantages offered from the total thyroidectomy, performed for benign diffused thyroid diseases, which surgical treatment "therapeutic" performed for these malignant tumors.The study was conducted on 600 patients operated with total thyroidectomy for benign thyroid disease, admitted from 1999 to 2003.All patients were alive and free of disease at last control.The MCT is a carcinoma that presents frequently a behavior little malignant and a good prognosis. His principal characteristic is the absence of clinical demonstrations. Therefore his discovery, almost always accidental on a thyroid removed for other pathology, it has signaled by histologic studyThyroid microcarcinoma is a slow growing tumor, with a good prognosis and with a good disease-free survival. It can present a better aggressiveness for his multifocal localization and invasion. Therefore total thyroidectomy can be considered best treatment and also be surgical treatment oncologically correct for this tumor.