Exhaust gas recirculation (EGR) in a high-pressure Common Rail Direct Injection (CRDI) engine: this study examines its result on combustion, performance, and emissions. Blends of diesel and Mahua oil biodiesel (marked B15 and B20, respectively) were created by adding varying amounts of the latter to the former. These fuel combinations with 20, 25, and 30% EGR rates were tested at a constant engine speed of 1500 rpm and a fuel injection pressure (FIP) of 900 bar. A reduction in brake thermal efficiency (BTE) of 11.9% was observed at 60% load and 16.9% at 100% load with 20% EGR, whereas reductions of 19% and 21.9% with B15 and B20 were observed with 25% EGR. Brake specific fuel consumption (BSFC) increased by 11.1% for B15 and 14.8% for B20. CO increases by 28.3% with B15 and by 27.0% with B20 at 30% EGR, while HC increases by 9.7% with B15 and by 8.5% with B20. At 30 % EGR, NOx emissions are 33% lower than with diesel fuel. © 2024 Elsevier B.V., All rights reserved.