Abstract Two cases of malignant neoplasm are presented briefly, and one of leukemia and one of arterial insufficiency are reported in detail. Exploratory laparotomy despite negative diagnostic surveys should not be delayed in patients over 40 who develop migratory thrombophlebitis which does not respond satisfactorily to anticoagulants. Inferior vena cava ligation is the surgical treatment of choice for those in whom no neoplasm is found as it is for those in whom anticoagulants cannot be used for any reason (individual sensitivity or lack of adequate laboratory facilities). Sequelae of inferior vena cava ligation such as those described by Shea and Robertson 10 need not be dreaded if proper elastic support and other medical measures are employed. 1, 2 Lumbar sympathectomy should be performed if arterial insufficiency is evident in order to promote increased arterial blood flow and remove one of the possible factors responsible for peripheral thromboses. Migratory thrombophlebitis still remains a most challenging therapeutic problem.