Biodiesel production generally involves the transesterification of vegetable and/or animal oils with alcohol and catalyst under conventional stirring with batch and/or continuous processes. In recent years, because of the economical causes, choosing efficient transesterification method for biodiesel production has become important. Using microwave method for the transesterification reaction supports high yields of highly pure products within a short time and a severe reduction in the quantity of by-products when compared to the conventional methods. In this study, transesterification of hazelnut oil was studied by using microwave-assisted method to examine reaction factors which affect the purity of the ester product, including the molar ratio of methanol to hazelnut oil, the amount of alkaline catalyst and the reaction time. The transesterification reactions were carried out by using hazelnut oil, methanol, and potassium hydroxide as the catalyst at 64 degrees C. A statistical design technique was applied by the use of a two-level factorial design matrix to interpret the experimental results. Empirical relations between the yield and the reaction conditions were developed. The experimental results indicated that microwave-assisted transesterification efficiently produced high yield of methyl esters in a short reaction time, showing that this method may be a promising alternative to the conventional method.