To assess whether dietary guidelines for Americans are appropriate for young children, the evolution of dietary guidance, the nature of the guidelines, evidence used to support the concept of diet modification to prevent heart disease and the rationale for extending application of the guidelines to children have been examined. As health improved during this century, life expectancy lengthened, and diseases associated with aging became major causes of death. As a consequence, emphasis on dietary advice for selecting a nutritionally adequate diet--the primary need of children--declined, whereas emphasis on dietary advice for preventing chronic and degenerative diseases increased. It is clear from reading the text accompanying the guidelines that they were proposed to prevent diseases of aging by reducing consumption of animal products. Critical evaluation of evidence bearing on the concept of the guidelines reveals that there are grounds for skepticism about claims for the effectiveness of diet modification as a measure for reducing the incidence of heart disease. Also, the rationale for extending the guidelines to young children is based on inferences from observations on adults, not on direct evidence that children will benefit from following them. There is, thus, ample justification for proposing separate dietary guidelines for children.