The use of recombinant DNA technology to produce genetically modified microorganisms is one of the most important scientific advances of the 20th century. It has great potential in research because it allows the development of highly sensitive analytical procedures. It also has potential in industry, leading to processes and products that would be difficult to develop using conventional techniques. These include food and food processing. The use of genetically modified microorganisms in food and food processing is controversial due to a lack of acceptance by consumers, especially in Europe. In this paper, we give specific examples of the use of gene technology at Chr. Hansen A/S to improve bacterial strain performance during the production of dairy products. We will also describe the technology involved, the results and the relevant legislation. (C) 1999 Elsevier Science Ltd. All rights reserved.