OBJECTIVE. The purpose of this study was to determine the spectrum of positron emission tomography (PET) with F-18-fluorodeoxyglucose (FDG) findings in patients who have primary pulmonary carcinoid tumors. CONCLUSION. On FDG PET imaging, pulmonary carcinoid tumors usually have lower FDG uptake than expected for malignant tumors. Biopsy or close radiologic follow-up is therefore recommended for solitary pulmonary nodules that are clinically suspected of being carcinoid tumors and that do not show increased metabolic activity on FDG PET images.