Tumors of the blood vessels are perhaps as common as any form of neoplasm occurring in the human body. The greatest number of these lesions are benign angiomas of the body surfaces, small elevated red areas which remain without symptoms throughout life and are not subjected to treatment. Larger tumors of this type which undergo active growth after birth or which are situated about the face or oral cavity, where they constitute cosmetic defects, are more often the object of surgical removal. The majority of the vascular tumors clinically or pathologically studied fall into this latter group. Benign angiomas of similar pathologic nature occur in all of the internal viscera but are most common in the liver, where they are disclosed usually at autopsy. Angiomas of the bone, muscle, and the central nervous system are of less common occurrence, but, because of the symptoms produced, a higher percentage are available for study.