Smoke and oxides of nitrogen are the most significant emissions of the diesel engines. Fuels, which have a high oxygen content have the potential to reduce smoke and nitrogen emissions. This paper reports the results of an experimental study on the influence of blending n-butanol, an oxygenated additive, with diesel on diesel engine emissions. N-butanol is blended with diesel in different proportions namely B5 (5% n-butanol and 95% diesel), B10, B15, B20, B25 and B30 and the effects on various emission parameters are studied. Tests were performed on a single cylinder, four stroke naturally aspirated diesel engine at a constant engine speed. Experimental test results show that the emissions of carbon monoxide, oxides of nitrogen and smoke opacity are reduced with increasing concentration of n-butanol in diesel .