Alcohols higher than methanol and ethanol have better ignition quality and energy density and are more compatible with compression-ignition engines. This study compares the effects of three alcohols: propanol (C3), butanol (C4), and pentanol (C5) as blending constituents with diesel by up to 40% (labeled as PRO, BUT, and PEN, respectively) on some critical characteristics of a direct-injection diesel engine. Some modifications in intake dilution via EGR and start of injection (SOI) were investigated. Results in comparison with diesel operation at similar operating conditions indicated that PEN had a shorter ignition delay than PRO and BUT. The peak pressures and peak heat release rates were highest for PRO followed by BUT and PEN under all conditions. The variations of injection timing had a superior effect to that of EGR on engine characteristics. Engine performance is of the order PRO > BUT > PEN. NOx reductions for PEN and BUT were better than for PRO. Smoke is lowest for PRO followed by BUT and PEN. At early SOIs, the combined effect of high combustion temperatures and oxygenated conditions of the blends offered appreciable EGR tolerance and kept the smoke emissions lower at EGR rates up to 20%. The higher alcohols can offer better performance and emission with certain modifications to the engine.