Left ventricular diastolic dysfunction is a well-described complication of systemic hypertension. However, less is known regarding the effect of chronic pressure overload on right ventricular (RV) diastolic function. We hypothesized that pulmonary hypertension (PHT) is associated with abnormal RV early relaxation and that this would be best shown by invasive pressure measurement. Twenty-five patients undergoing right heart catheterization for investigation of breathlessness and/or suspected PHT were studied. In addition to standard measurements, RV pressure was sampled with a high-fidelity micromanometer, and RV pressure/time curves were analyzed. Patients were divided into a PHT group and a non-PHT group on the basis of a derived mean pulmonary artery systolic pressure of 25 mmHg. Eleven patients were classified to the PHT group. This group had significantly higher RV minimum diastolic pressure (5.1 ± 6.6 vs. −0.1 ± 3.3 mmHg, P = 0.03) and RV end-diastolic pressure (RVEDP; 11.0 ± 6.3 vs. 3.8 ± 3.7 mmHg, P = 0.004), and RV τ was significantly prolonged (53 ± 32 vs. 31 ± 13 ms, P = 0.04). There were strong correlations between RV τ and RV minimum diastolic pressure (r = 0.93, P < 0.0001) and between RV τ and RVEDP (r = 0.87, P < 0.0001). There was a trend toward increased RV contractility (end-systolic elastance) in the PHT group (0.73 ± 0.21 vs. 0.52 ± 0.21 mmHg/mL, P = 0.07) and a correlation between RV systolic pressure and first derivative of maximum pressure change (r = 0.58, P = 0.003). Stroke volumes were similar. Invasive measures of RV early relaxation are abnormal in patients with PHT, whereas measured contractility is static or increasing, which suggests that diastolic dysfunction may precede systolic dysfunction. Furthermore, there is a strong association between measures of RV relaxation and RV filling pressures.