Pulmonary artery compliance (PAC) contributes to right ventricular (RV) afterload, is decreased in the setting of increased left ventricular (LV) filling pressures, and may be an important component of World Health Organization (WHO) group II pulmonary hypertension (PH). Left ventricular assist device (LVAD) implantation can rapidly change LV filling, but its relationship with PAC is unknown. Right heart catheterization was performed preoperatively, postoperatively (between 48 and 72 hours), and >30 days post-LVAD implantation in a cohort of 64 patients with end-stage systolic heart failure. Within 72 hours, LVAD implantation was associated with an increase in PAC (2.0-3.7 ml/mm Hg, p < 0.0001), a decrease in pulmonary vascular resistance (3.5-1.7 Wood units, p < 0.0001). Pulmonary arterial compliance did not increase further at the >30 post-LVAD time point (3.7 ± 1.7 to 3.6 ± 0.44 ml/mm Hg, p = 0.44). Pulmonary artery compliance improves rapidly after LVAD implantation. This suggests that more permanent changes in the pulmonary vascular bed may not be responsible for the abnormal PAC observed in WHO group II PH.