Triterpenes are a versatile group of biologically active ingredients present in several phytoextracts. They often occur as glycoconjugates with a distinct bioactivity from their aglycone counterparts. Deglycation of triterpenes can be performed by enzymatic and chemical reactions, whereas biotransformation is generally more specific and occurs without unwanted alterations to the molecule. Further structural modification of the triterpenes to enhance their pharmaceutical relevance can be efficiently carried out by the application of biotransformational processes using microorganisms or isolated enzymes. In particular, the whole-cell process is favorable if cofactor-dependent modifications are preferred, such as hydroxylations/oxidations of the lead compound. However, the isolation of triterpenes from domestic plant material has some disadvantages such as extract variability and instability. These problems can be overcome through the use of cell culture technology, where the ex vivo cultivated cells are used for the reproducible production of the target compound. The relevant topics that should be addressed to establish a (biotransformational) production process of pharmaceutically relevant triterpenes are covered in this review. In particular, we focus on the production process using tissue engineering, the corresponding analytical techniques, and the biotransformation reaction required to obtain bioactive compounds from precursor molecules. (C) 2010 Elsevier Ltd. All rights reserved.