This brief review article has been intended to give a few up-to-date examples of the dramatic impact that our knowledge of gene expression (especially bacterial gene expression) has had in the area of biotechnology. This area is in a state of such rapid growth that it has only been possible to present a limited overview of the subject matter. We have tried to illustrate our points with examples from work in which we have had some direct involvement. It should be apparent that continued increase in our understanding of gene expression should provide additional opportunities for expanded application of the new methodology.