1. Thromboembolism occurred in three (3.56 per cent) patients given warfarin as opposed to twenty-one(28.7 per cent) of those who did not receive anticoagulant therapy. In two of the three patients treated, anticoagulation was instituted late and in the third patient a treatment free interval of nine days occurred.
2. Hemorrhagic complications encountered in both groups of patients did not differ significantly. One major bleeding complication that occurred in the group of patients treated with warfarin could have been avoided if a history of peptic ulcer had been available. In all instances, bleeding complications occurred when the prothrombin activity was below 20 per cent of normal.
3. The results in the present survey are comparable with previous reports and further reaffirm the value and practicality of this form of prophylaxis.