Imaging with Tc-99m labeled red blood cells (RBC) is increasingly being used in the detection of acute gastro-intestinal bleeding, especially in patients with intermittent bleeding. A patient is presented in whom the labeled RBC scan was helpful in the incidental discovery of a previously unsuspected probable angiosarcoma of the right femur and adjacent soft tissues of the right hip due to the "blood pool" or "blush effect" of the labeled cells. The labeled RBC scan also identified extravasation due to active gastrointestinal bleeding from a previously unknown angiosarcoma of the ascending colon. Thus, the Tc-99m labeled RBC scan was useful in simultaneously detecting extravasation and blood pool effect at two remote tumor sites in the same patient.