Thrombotic complications dominated in the group treated with bishydroxycoumarin (12, compared to 5 in the heparin group). Embolic complications predominated in those treated with heparin (five, compared to one in the bishydroxycoumarin group). Of 52 patients receiving adequate bishydroxycoumarin therapy, 16 died; 8 in the group of 12 died while receiving inadequate therapy. Of 75 with adequate heparinization, 16 died; 12 out of 25 died with inadequate heparin therapy. Three or more complications were followed by death in 11 of 19 given bishydroxycoumarin and 14 of 60 given heparin.