Fusel oil is a by-product from alcoholic fermentation. GC-MS study shows that fusel oil consist of alcohols, ether, and cyclopentane. A based diesel oil was blended with 2, 4, 6, 8 and 10% V/V of fusel oil. Blended fuels were tested with the 4JA 1L ISUZU diesel engine for studying the effect of fusel oil on PAHs. The engine speed was varied at 800, 1600, and 2400 rpm. All exhaust emission samplings were extracted and analyzed for PAHs by GC. It was found that 9 species of PAHs including naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(b) fluoranthene were found in exhaust emission. The amount of PAHs found when use a based diesel oil at the engine speed of 800 rpm is 32.12 ppm. However, 28.96 ppm of PAHs was found when blended fuel containing 10% V/V of fusel oil was used in the diesel engine and the engine speed was 2400 rpm. The physical properties of the blended fuel were tested following the ASTM methods and found that the blended fuel has low flash point, low distillation point, and high water content.