Studies to determine the biological age of a person are a major concern of gerontological research today. The use of test batteries is now a proven method, and the procedure developed in Leipzig covers 47 parameters including physical, mental, and social data. It can be seen from the related findings that this approach is suitable for dealing with specific questions in gerontology. These include the detection of medical risk factors and environmental effects, and confirmation of intervention strategies. The prime motives behind these studies then seem to be in keeping with practical requirements.