Experience with patients undergoing left ventricular assist device (LVAD) implantation with preexisting mitral valve prostheses is limited. Patients with mechanical heart valves might have an increased risk of thromboembolism; in patients with biologic valves, there might be a risk of structural deterioration of the leaflets. Out of 597 patients supported with a LVAD system between 2000 and 2009, 18 patients had mitral valve surgery prior to implantation. We excluded all patients below 18 years of age, those with postcardiotomy failure, and patients who had had mitral valve reconstruction. Only 1% of the studied patient population (n= 6) had mitral valve replacement. The mitral valve implantation has been performed 7.4 ± 9.4 years prior to LVAD insertion. None of the valves (one biologic, five mechanical) were exchanged or explanted. LVAD implantation was done either with left lateral thoracotomy (n= 5) or with midline resternotomy (n= 1). Temporary right ventricular assist device support was necessary in one case (16.6%); 30-day mortality was 16.6% (n= 1). Median support time was 14 ± 15 months. Two patients received heart transplantation after 6 and 26 months on the device; four patients died on mechanical circulatory support after 1, 2, 5, and 40 months. No valve or pump thrombosis or other clinically relevant thromboembolic events were observed. Only a small number of patients (1%) had a preexisting mitral valve prosthesis prior to LVAD implantation. No severe adverse events were observed when the prosthesis was left in place. Attention should be paid to the anticoagulation regime.