The spectrum of vascular tumors ranges from hemangioma (HEM), to epithelioid hemangioendothelioma (EHE) and to angiosarcoma (AS). To the best of our knowledge, the usefulness of F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for vascular tumors has never been comprehensively studied. The present study investigated the usefulness of FDG-PET for pathologically diagnosed vascular tumors. The present study included 26 patients with vascular tumor (male:female, 17:9; age, 60.9±14.4 years; 7 HEM, 6 EHE and 13 AS) who underwent FDG-PET between January 2007 and May 2014 at the Seoul National University Bundang Hospital (Seongnam, Korea) and Konkuk University Medical Center, (Seoul, Korea). Representative FDG uptake was measured as the maximum standardized uptake value (SUVmax) over the lesion with the highest FDG uptake. Disease progression was clinically defined as the aggravation of known lesions or novel lesion development during follow-up on computed tomography, magnetic resonance imaging, or FDG-PET. FDG-PET revealed multi-organ involvement only in AS (6/13 [46.2%]), whereas HEM and EHE involved a single organ. Tumor SUVmax was significantly greater in AS (6.32±4.84) compared with EHE (3.10±2.68) and HEM (2.33±0.76) (P=0.0284). There was no difference in tumor SUVmax between HEM and EHE (P>0.05). Disease progression was primarily noticed in AS (9/13 [69.2%]). Only 1 patient with EHE (1/6=16.7%) and no patients with HEM (0/7=0%) experienced disease progression. Mortality was reported only in patients with AS (4/13 [30.8%]). Using the cutoff SUVmax of 3.0, the two-year progression-free survival rate of 14 patients with tumor SUVmax <3.0 (75.0%) was significantly higher compared with that of 12 patients with tumor SUVmax ≥3.0 (0%) (P=0.0053). In conclusion, FDG-PET is useful for the differential diagnosis and prognosis prediction of vascular tumors.