Introduction: Extreme haemodilution going on with cardiopulmonary pass imposes an vital chance element recollect for blood transfusion in cardiac surgical patients. Priming of the cardiopulmonary bypass circuit with sufferers! own blood [retrograde autologous priming (RAP)] is a system used to restrict haemodilution and decrease transfusion requirements. Objective: The objective of our study was to evaluate the effects of Retrograde Autologus Priming on reducing intraoperative blood transfusion in cardiac surgery. Methodology: It was cross sectional study, conducted over a period of six month from august 2021- February 2022 at Peshawar Institute of Cardiology, department of cardiac surgery. We enrolled one hundred and sixty patients, n= (160) through pre-structured Performa by the use of non-probability convenient sampling method technique. Results: The mean age of the patients (8.77±8.644), mean HB before surgery (13.443±2.9020), after surgery (10.947±2.0891), haematocrit after surgery (34.98±7.697), priming volume (549.32±229.013), effective priming volume (539.69±257.563), extubation time (3.91±1.255) and ICU stay was (2.20±.875). Post-op performance HB level, hematocrit, priming volume, extubation time and ICU stay shows a significant association at p value