The understanding of paraneoplastic syndromes has improved over the last several years. These disorders are brought about by tumor secretion of substances that can alter hormonal function and create immune cross-reactivity with normal tissues. This, in turn, can alter normal metabolic pathways resulting in paraneoplastic syndromes. The athlete must maintain an awareness of their body because these syndromes affect diverse organ systems. Commonly associated malignancies include small cell lung cancer, breast cancer, gynecologic tumors, and gastroenterological malignancies. These cancers most notably affect the neuromuscular, rheumatologic, mucocutaneous, hematologic, renal, and endocrine systems. Effective diagnosis and treatment of paraneoplastic syndromes most often require appropriate diagnosis and treatment of the underlying malignancy. This review focuses on the most commonly encountered paraneoplastic syndromes, so athletes and those who care for them can be aware of the potential risk of an occult or recurrent malignancy.