Since 1988, 295 patients have undergone MCS at the German Heart Institute Berlin; 246 received biventricular support with the extracorporeal pneumatically-driven Berlin Heart Assist Device, 49 received left ventricular support with implantable assist devices (33 Novacor, 16 TCI). Longer waiting periods for heart transplantation has caused the mean duration of MCS to increase from 12 days in 1988 to 76 days in 1994. Of the 24 patients who underwent MCS for more than 90 days, nine were implanted with a biventricular device, 12 with a Novacor device, and 15 with a TCI device. Eight patients with uni-ventricular devices remain on support after 200 days (range 203-600 days). Six of the Novacor patients could be discharged to a nursing home or to their own residences. One patient still on NC support after more than 600 days currently resides at his home and has regained normal physical activity. Minor pocket infections occurred in two TCI and four Novacor patients; one patient died of sepsis. A total of four patients could be weaned from LVAD after 160-347 days of MCS. An initial high level of beta1 receptor antibodies disappeared completely during left ventricular support. This decline in auto-antibodies was paralleled by a dramatic improvement in cardiac function. LVEF remained unchanged up to 6 months after explantation. Long-term mechanical support has become a reality. Heart transplantation after prolonged MCS yields results comparable to primary HTx. Some patients exhibit immunological changes and a dramatic improvement in ventricular function under long-term MCS and can be weaned with extremely satisfying results.