A 6 year experience with the bileaflet St. Jude Medical valve is reported. Between Feb. 1986 and Dec. 1992, 68 patients received 87 such valves[36 mitral, 13 aortic, and 19 double mitral-aortic valve replacements]. The results are summarized as follows 1. There were 35 male and 33 female patients ranging in age from 17 to 55 years the mean age of 35.3 $pm$ 9.7 years. 2. The mean aortic clamp time[ACT] of the MVR, AVR and DVR groups were 91.5$pm$16.4, 117.2$pm$28.7 and 165.5$pm$24.1 minutes. The mean total bypass time [TBT] of the MVR, AVR and DVR groups were 112.8$pm$19.5, 134.7$pm$31.4 and 192.2$pm$28.5 minutes. 3. Eighty seven valves were used [55 mitral site, 32 aortic site]. 31mm[20], 33mm[15], 29mm[15], 27mm[2], 25mm[2] and 35mm[1] were used in mitral site and 23mm[13], 21mm[8], 19mm[7] and 25mm[4] were used in the aortic site. In the DVR, there were valve combinations such as 4 cases of M[29mm]-A[19mm], 4 of M[31mm]-A[23mm], 3 of M[33mm]-A[23mm] and others. 4. Preoperative NYHA functional classes were II [3 cases], III [46 cases], IV[19 cases] and improved to I [52 cases] and Il [13 cases] postoperatively. 5 Early postoperative complications were occurred in 15 cases[2Z.l%] and there were LOS in 5 cases[7.4%], arrythmia [3 cases], wound infection [2 cases], hepatitis [2 cases], sudden cardiac arrest [2 cases] and postoperative bleeding [1 case]. The early hospital death was occurred in 3 cases[4.4%] with LOS [1 case] and sudden cardiac arrest [2 cases]. 6. Mean follow-up time of survival cases[65 cases] was 31.3$pm$21.9 months and the total follow-up time was 169.8 patient-years. Late postoperative complications were occurred in 4 cases[2 thromboembolism, 1 paravalvular leak, 1 thromboembolism br paravalvular leak, 1 valve endocarditis] with the occurrence rate as 2.35% per patient-years. Reoperation was performed in 2 cases [1 paravalvular leak, 1 left atrial thrombus] and there was one [1.5%] late valve related death. Therefore the 6 year complication free rate was 90.6% and 6 year actuarial survival rate was 98.3$pm$1.7%. On the basis of this experience and the results, SJMvalve appears to be one of the best performing mechanical prosthesis currently available, in terms of both hemodynamics and lower complications with warfarin antioagulation.