Oat cell or undifferentiated small cell carcinoma is a rare malignant tumor of the larynx. Since this lesion was first described, only 23 cases have been reported in the literature. Oat cell carcinoma of the lung, however, accounts for 20% to 25% of all lung cancers and is frequently associated with a variety of paraneoplastic syndromes. A 64-year-old woman had a primary oat cell carcinoma of the supraglottic larynx associated with clinical and electromyographic evidence of the myasthenic syndrome of Eaton-Lambert. To our knowledge, this is the first description an oat cell carcinoma of the larynx associated with this syndrome, which supports the theory that oat cell cancers of the larynx and lung have a common histogenesis.