Three patients, undergoing surgery for pharyngeal carcinoma, were studied after their informed consence in the aim of ascertaining: 1) whether the routinary hemithyroidectomy in case of surgical treatment of the cancer of pyriform sinus is justified by a real probability of neoplastic invasion of the gland, and 2) which pathway the neoplasia follows in the metastatic process. In each patient a small amount of methylene blue solution was injected in the pyriform sinus submucosa, just before starting the surgical operation, currently including hemithyroidectomy. The stain spreads to the superior portion of the thyroid lobe, and seems to follow the periarterial lymphatic vessels. Even if further researches are necessary, the obtained data seem to justify routinary thyroidectomy in course of surgical treatment of the hypopharyngeal cancer.