1. Patients subjected to TDD prior to transplantation had a 4-yr graft survival rate of 65% compared to a comparably HL-A-matched group in which the survival rate was 35%9 2. Patients classified as non-responders to tissue antigens have a much higher graft retention rate than responders. Responders subjected to TDD have a 1 yr graft survival rate of 62% compared to a comparably HL-A-matched group with a survival rate of 28%. 3. Individuals with a positive crossmatch or receiving second or third transplants and subjected to TDD do much better than such individuals not subjected to TDD.