Engine tests were carried out with several mixing ratios of fuel between sardine oil and diesel in a diesel engine. The high viscosity of sardine oil leads to problem in pumping and spray characteristics. The improper mixing of sardine oil with air leads to incomplete combustion. The best way to use sardine oil as fuel in diesel engines is to convert it into biodiesel. It can be used in diesel engines with out any engine modifications. This is because it has properties similar to mineral diesel. Combustion tests for methyl ester of sardine oil and its blends with diesel fuel were performed in a kirloskar TAF1 DI diesel engine, to evaluate sardine biodiesel as an alternative fuel for diesel engine, at constant speed of 1500 rpm under variable load conditions. The tests showed that break thermal efficiency is slightly increased and HC, CO in the exhaust are reduced when fuelled with methyl esters compared to diesel except NO<inf>x</inf> emission. © 2013 Elsevier B.V., All rights reserved.