The transesterification reactions of castor oil with ethanol and methanol as transesterification agents were studied in the presence of several classical catalytic systems. The effects of the nature of the alcohol and catalyst on the yields of monoalkyl fatty acid esters were evaluated. The results indicate that biodiesel can be obtained by transesterification of castor oil using either ethanol or methanol as the transesterification agent. Similar yields of fatty acid esters may be obtained following ethanolysis or methanolysis; however, the reaction times required to attain them are very different, with methanolysis being much more rapid.