Paraneoplastic syndromes may be the presenting clinical manifestation of small cell lung cancer. In some cases, however, confirming the diagnosis can be difficult because findings on conventional imaging studies can be subtle or nonspecific. This study examined the utility of fluoro-2-deoxy-glucose positron emission tomography (FDG-PET) in identifying clinically suspected small cell lung cancer in patients with paraneoplastic syndromes. FDG-PET appears to be very useful in localizing suspected small cell lung cancer in patients presenting with paraneoplastic syndromes.