Paraneoplastic syndromes are disorders of host organ function occurring at a site remote from the primary tumor and its metastases. Paraneoplastic syndromes associated with primary lung cancer are not uncommon, have diverse initial manifestations, and epitomize the systemic nature of human malignant disease. The spectrum of clinical features in patients with paraneoplastic syndromes is very wide. Although diagnosis is often one of exclusion, improved understanding of the pathogenesis involved in some of these syndromes has provided another means of recognizing these disorders and perhaps treating affected patients. In this update, we review paraneoplastic syndromes associated with lung cancer, potential mechanisms, clinical manifestations, diagnosis, and treatment.