Iodinated I 131 serum albumin injected into laryngeal carcinoma tissue spreads through lymphatic pathways to the cervical lymph nodes. The concentration of albumin in the lymph nodes is irregular, and specific activity of lymph nodes from the same patient varies over a wide range. In advanced laryngeal carcinoma, irrespective of its localization and of the site of injection of albumin, lymph nodes with maximum specific activity were observed on both sides of the neck.