Biodiesel, an ideal alternative to fossil fuels, is very imperative for the sustainable development of mankind. Among its preparation technologies, biotechnological preparation is the most promising one. This study critically reviews the current progresses in biocatalysts (lipases), transesterifaction, feedstocks, and, particularly, the key aspects that have been neglected or have recently emerged. A complete summary of the development of stable and cost-effective lipases, ultrasonication and microwave-assisted treatment for biodiesel synthesis, solvent engineering, synergetics of different lipases, kinetics and reaction mechanism for enzymatic transesterification, potentially cheap feedstocks, and economic efficacy analysis has been provided. As a bulk commodity with low revenue, biodiesel production is strongly affected by the prices of oil feedstocks. Hence, value-added derivatives are highly significant. This topic has been highlighted and comprehensively addressed in this review for the first time. (C) 2013 Elsevier Ltd. All rights reserved.