We evaluated right ventricular (RV) diastolic performance in 12 healthy subjects (control), 25 patients with chronic pulmonary diseases (CPD) and 6 patients with chronic pulmonary thromboembolism (PTE). Flow velocity patterns were determined by the pulsed Doppler technique. The values determined included acceleration time (AT), deceleration time (DT), and the ratio of the atrial contraction wave (A) to the rapid filling wave (R) (A/R ratio) from flow velocity patterns in the RV inflow tract. DT was significantly prolonged in the CPD and PTE groups compared with the control group, indicating dysfunction during the early (middle) filling period. The prolongation was marked in those patients with pulmonary hypertension. The A/R ratio was significantly higher in the CPD and PTE groups than in the control group, indicating a decrease in RV compliance. The A/R ratio increased slightly with the increase in the end-diastolic volume index. These results suggested that the pressure overload plays an important role in RV diastolic dysfunction in patients with pulmonary disease, and that preload contributes to the dysfunction.