The present investigation is aimed to find the influence of fumigated calophyllum inophyllum biodiesel vapors on the combustion, performance, and emissions of a single cylinder, four strokes, water cooled, direct injection diesel engine. Biodiesel produced by transesterification of calophyllum inophyllum oil was used as alternative fuel in this investigation. The performance, emission and combustion characteristics of the diesel engine with four different fumigated calophyllum inophyllum biodiesel ratios (5%, 15%, 25% and 35% by vol. basis) are compared with diesel fuel and presented in this paper. The experimental results indicate 12.27% higher brake thermal efficiency with fumigated calophyllum inophyllum biodiesel 15%, and the brake specific fuel consumption was found to be higher by 18.63% when compared to that of diesel fuel. The maximum heat release and peak pressures obtained with calophyllum inophyllum biodiesel ratios 5% and 15% are 5.09%, 9.8% and 3.76%, 5.9%, respectively, higher than diesel fuel at full load conditions. The oxides of nitrogen and smoke emissions were decreased by 20.02% and 8.1%, respectively.