Existing studies on sexual behavior of the aged show earnest deficiencies: false sampling, insufficient interviewing instruments and little interest in theory development. As a consequence all results must be taken as preliminary: most elderly reduce their sexual activities and change from genital to tenderness behavior. Men and women experience sexuality differently. Those who live in institutions report of few sexual interest and complain of lacking privacy. Several theories are applied to sexual behavior of the aged: disuse, exchange, role, communication theories and the concept of developmental tasks. Some consequences for research, for the elderly, for the social environment, for sex education and for institutions are discussed.