Intravenous (IV) leiomyomatosis is a rare IV disease. Our case presents 68 Ga-FAPI and 18 F-FDG PET/CT findings of IV leiomyomatosis in a 37-year-old woman. Intravenous leiomyomatosis shows only mild FDG but intense 68 Ga-FAPI activity on PET/CT studies. In this case, 68 Ga-FAPI was superior to 18 F-FDG PET/CT in detecting IV leiomyomatosis.