To reduce the nitrogen oxides (NOx) formation, the automotive industry uses the Exhaust Gas Recirculation (EGR) technology. The main objective of the present work is to numerically investigate the influence of EGR on pollutant emissions in non premixed regimes. The influence of EGR composition and percentage in a counterflow diffusion flame has been investigated. 0-D computations have been performed to characterize the EGR composition. Counterflow flame simulations for various EGR compositions and percentages show that chemical effects on heat release and pollutant production are significant.