Developments in biotechnology have been extremely rapid the last two decades. This is particularly true for recombinant DNA technology, which has strongly stimulated the study of biocatalysis, and many examples of new applications of biocatalysts exist. Nevertheless, they have not yet been routinely applied in chemistry. In this study, the question is addressed as to when biocatalysts can be advantageously used in this field. If that is indeed the case, many decisions have to be made before they can be optimally utilized. In the present work, a decision tree is introduced which provides important questions to answer to come to such an optimal use. Examples are given to illustrate the decisionmaking.