Background: Infants of diabetic mothers (IDMs) have impaired myocardial performance and are at risk of pulmonary hypertension. Aim of the work: to evaluate the precision of doppler echocardiography-derived pulmonary artery acceleration time (PAAT) in estimating pulmonary artery pressure in infants of diabetic mothers and to compare it to the conventional method by using tricuspid regurgitation velocity. Studied cases and techniques: A comparative cross-sectional study, which included (30) infants of diabetic mothers, with a mean age of 3.4 ± 1.5 days, who were admitted to the neonatal intensive care unit (NICU) of Ain Shams University's hospitals, because of elevated pulmonary pressure, as a case group, and (30) healthy age- and gender-matched neonates as a control group. Transthoracic echocardiography & doppler echocardiography-derived PAAT was done at 1st week of life. Results: The study revealed a substantially significant decrease in the level of PAAT (p<0.001) and an increase in the level of systolic pulmonary artery pressure (SPAP) in the group of IDM diagnosed with pulmonary arterial hypertension compared with the control group. Also, according to research, there was a substantial negative relationship found among the level of PAAT (ms) & level of SPAP (mmHg) in the cases group (r =-0.984 and p<0.001). PAAT ≤72 ms had 96.67% sensitivity and 93.33% in identifying studied cases with pulmonary arterial hypertension in IDMs. Conclusions: PAAT measures can be used as an alternative to the conventional method. PAAT ≤72 ms can serve as a strong, non-invasive predictor of pulmonary arterial hypertension in infants of diabetic mothers.