Positron emission tomography (PET) with fluorodeoxyglucose (FDG) was performed for preoperative staging of lung cancer. In six of 184 patients, there was an intense FDG accumulation in the lower anterior neck. Fusion of PET and computed tomographic images revealed that the focal FDG uptake was localized in the internal laryngeal muscles. This finding was a result of compensatory laryngeal muscle activation caused by contralateral recurrent laryngeal nerve palsy due to direct nerve invasion by lung cancer of the left mediastinum or lung apices. The knowledge of this pitfall is important to avoid false-positive PET results.