An association between polymyositis and lung cancer has been debated. Published data usually lack either lung cancer histologic differentiation or biopsy-based delineation between polymyositis and dermatomyositis. We reported a case of a 56-year-old man with squamous cell carcinoma of the lung confined to a single hilar lymph node presenting with biopsy-proven polymyositis of 3 months in duration. Polymyositis should be considered as a potential presentation of paraneoplastic syndrome, especially in patients who are at risk for lung cancer.