The effect of high pressure loop (HPL-) and low pressure loop (LPL-) EGR systems on engine performance and emission characteristics were investigated using a multi-cylinder diesel engine under steady-state conditions. The HPL-EGR achieves higher fuel economy at low load while the LPL-EGR can sufficiently lower intake gas temperature and can reduce NOx and soot emissions. Especially at high load, LPL-EGR can reduce NOx and soot emissions without fuel penalty. At low load, on the other hand, the LPL-EGR can reduce NOx to meet the post new long-term regulation target without increasing soot emission than HPL-EGR baseline.