We report three rare cases of typical carcinoid of the lung accompanied by elevation of serum pro-gastrin-releasing peptide (proGRP). The patients had no symptoms, but they had abnormal shadows on chest X-ray. Their serum proGRP concentrations were 177, 176, and 572 pg/ml. Chest CT revealed solitary pulmonary nodules, which were homogeneous, well demarcated, and round. One patient underwent FDG PET-CT, and the FDG uptake was lower than expected for malignant tumors. Dynamic enhanced MRI showed high vascularity in all tumors, which suggested malignancy. After surgical resection, the proGRP levels decreased to the normal range. We encountered three rare cases of Stage I typical carcinoid accompanied by elevated serum proGRP levels. It is important to consider a possibility of carcinoid in solitary pulmonary nodules with elevation of the proGRP level. These cases suggest that the combined use of dynamic enhanced MRI, FDG PET-CT, and serum proGRP can be a useful tool for diagnosing carcinoid before surgery.