alpha-L-Rhamnosidase [E. C. 3.2.1.40] cleaves terminal alpha-L-rhamnose specifically from a large number of natural products. The enzyme has wide occurrence in nature and is reported from animal tissues, plants. yeasts, fungi and bacteria. It is a biotechnologically important enzyme due to its applications in debittering and clearance of citrus fruit juices, enhancement of wine aromas and derhamnosylation of many natural products containing terminal alpha-L-rhamnose to compounds of pharmaceutical interests. Though alpha-L-rhamnosidases have been investigated actively during recent years, there is no recent review on alpha-L-rhamnosidases. An attempt has been made to fill up this gap in this review. It consists of a brief introduction of alpha-L-rhamnosidase which is followed by a critical description of the methods used for assaying the enzyme activity. Purifications, characterizations and properties of alpha-L-rhamnosidases from different sources have been discussed and the available structural and molecular biological studies on the enzyme have been given. Biotechnological applications of this enzyme in different processes have been briefly described. The review concludes with the identification of areas which needs further extensive studies. (C) 2010 Elsevier Ltd. All rights reserved.