Inedible vegetable oils that can be extracted from unexploited forest produce can provide solutions to energy requirements at the grass roots level, thus obviating dependence on fossil fuels. Short-term compression ignition engine tests were carried out using karanj (Pongamia pinnata) oil alone and also by blending it with diesel. The calorific value of karanj oil was 14.77% less than that of diesel. Due to its high viscosity (28.63 at 40C), the brake specific fuel consumption and brake thermal efficiency were observed to be higher and lower, respectively, in the case of karanj oil, than those obtained from diesel. But, by blending karanj oil with diesel, the difference was minimized. The performance of karanj oil was comparable to that of diesel when blended with it in 20:80 (v/v) ratios. The smoke density and total hydrocarbons in the emissions of K20 blend were higher than that of diesel fuel, but considerable reductions in CO and NOx were obtained.