Pulmonary embolism continues to kill a large number of hospitalized patients. Until adequate prophylactic measures are available, reliance must be placed on early diagnosis and immediate treatment of clinically detectable phlebitis. This is particularly true for patients with heart disease, which is the most common and ominous condition predisposing to thromboembolism. Thrombophlebitis and phlebothrombosis are different clinical manifestations of the same pathological process and should be treated with equal vigor. Carefully planned surgical vein interruption proved superior to anticoagulant therapy at the Boston City Hospital, particularly in the chronic predisposing states such as cardiac disease or hemiplegia. Post-phlebitic symptoms such as edema, varicose veins, and ulcers occurred as frequently after anticoagulant treatment as after surgery and appeared related to the extent of the initial disease rather than its treatment.