Non invasive estimation of pulmonary artery pressure (PAP) is of paramount importance in various form of cardiac, respiratory and intensive care medicine practice. Using pressure gradient between different chambers enables a reliable estimation of PAP and are being largely practiced. In absence of these pressure gradient, various time interval or the ratios of pulmonary blood flow velocity curve (PBFVC) in pulsed wave doppler echocardiography (PWDE) can predict the PAP. But there is lack of general agreement as which parameter should be used. We hypothesized that using separate time interval or their ratios of PBFVC for different group of patient may improve the PWDE prediction of PAP. Forty-six consecutive patients with different cardiac diseases and 20 consecutive control persons underwent PWD echocardiographic examination. Pulmonary blood flow velocity curve derived time intervals--the time intervals--time to peak velocity (TPV), Pre-ejection period (PEP) and right ventricular ejection time (RVET) and their ratios were measured. The Doppler derived measurements were compared with cardiac catheterization (CC) measured PAP in 46 patients in whom CC were done. PBFVC derived time interval TPV and the ratio PEP/TPV correlated well with CC measured systolic PAP (r=-0.78 and r=0.77 respectively). For congenital left to right shunt disease the ratio PEP/TPV improved the prediction (r=-0.87) while the same measure showed weak correlation in patients with left sided heart disease. Only TPV could predict mean PAP in patients with left sided heart disease (r=-0.60). We concluded that the use of separate PBFVC derived time interval or their ratio from PWDE may improve the prediction of PAP with different pathological group of disease.