Elderly people, those above 60 or 65 years old differ from younger people in many ways. Nuclear medicine can play a role in the diagnosis of diseases of the elderly and thus help, in social adjustment and in care for the elderly people. The question is why adult stem cells have a certain limit of reproduction, since their DNA in a normal physical environment can theoretically live very much longer. The elderly are prone to suffer more diseases than the young. It is important that the elderly should use water soluble and not lipid soluble drugs. There are many more to write about the elderly. We have tried to be brief in order to show the importance of using nuclear medicine in gerontology. Let us mention here that the word gerontology means in greek "talk about the elderly" (gerontas is the old man and logy is to talk about). Elderly people are a large part of our society and we do have every reason, every interest and responsibility to keep this part of our society healthy, useful and productive.