Pancoast-Tobias syndrome is a rare entity, defined by a clinical triad of cervicobrachial neuralgia in the C8-D1 territory, hand amyotrophy and Claude-Bernard-Horner syndrome, secondary to a tumor of the pulmonary apex. However, there are incomplete or misleading forms that can lead to a wrong diagnosis. The purpose of our observation is to study the clinical and electroneuromyographic patterns of brachial plexus involvement in Pancoast-Tobias syndrome.