In thirty-five consecutive patients, operated on under tourniquet, an intensive search for thrombophlebitis disclosed twenty patients with positive venograms for fresh thromboses and eight of ten with previously positive venograms had evidence of fresh thromboses. In sixteen of the twenty patients the symptoms and signs were suggestive of fresh thromboses. Three patients had pulmonary embolism and one had pulmonary infarction. The presence of rheumatoid arthritis and history of corticosteroid therapy could not be specifically related to the frequency of thrombosis.