Non-invasive measurement of blood pressure in patients with a left ventricular assist device (LVAD) is challenging due to the mechanical properties of these circulatory support devices. Keeping blood pressure in a target range is crucial to reduce the risk of LVAD complications. As current assessment methods require trained personnel resulting in infrequent monitoring, devices for home-based measurements are sorely needed. In this paper, we report a measurement method and a custom-made monitoring device based on photoplethysmography (PPG) enabling automated measurement of the mean arterial pressure (MAP) of patients with LVAD. The method and the device were tested on 21 adult patients with LVAD, and the estimated MAP values were compared to MAP values measured simultaneously by a human expert applying the commonly used Doppler-based method. Results of the proposed method showed highly significant correlation with Doppler-based MAP values (R = 0.85 for inflation, p < 0.001; R = 0.96 for deflation, p<0.001). The mean difference of the proposed method to the Doppler-based MAP values was 1.48 ± 5.43 mmHg for inflation and -0.19 ± 2.71 mmHg for deflation. The results demonstrate that the proposed method is a promising direction to achieve accurate, automated, non-invasive BP measurement, applicable in home health monitoring for patients with LVAD.