Biodiesel can be produced from a number of natural, renewable sources, but vegetable oils are the main feedstocks. Most existing biodiesel plants currently rely upon the use of a homogeneous catalyst in a continuous reactor system, using the transesterification of soybean or rapeseed oil with methanol into alkyl esters. A key differentiation characteristic among the existing processes is that of the mixing pattern employed in the system. The present study compares reactor performances in terms of biodiesel yields for plug flow and complete mixing behaviors, along with the use of interstage phase separation. It is concluded that plug flow pattern shows a distinctive benefit in terms of yields and reactor volume reduction compared to complete mixing. Interstage separation improves the reacting system yields when proper phase separation can be achieved, maximizing glycerine removal from the downstream system. Staged mechanically stiffed tank reactors can reach similar performances as plug flow behavior systems without resorting to interstage separation under the conditions here studied. Methanol/oil ratio can improve the reacting, system performance and reduce differences, even if plug flow reactors are not employed.