This review discusses nutrition and related health problems among homeless Americans, summarizes recent information, and identifies needs for services and future research. The nature of homelessness today provides a context for the discussion. Many homeless persons eat fewer meals per day, lack food more often, and are more likely to have inadequate diets and poorer nutritional status than housed U.S. populations. Yet many homeless people eligible for food stamps do not receive them. While public and private agencies provide nutritious food and meals for homeless persons, availability of the services to homeless persons is limited. Many homeless people lack appropriate health care, and certain nutrition-related health problems are prevalent among them. Compared with housed populations, alcoholism, anemia, and growth problems are more common among homeless persons, and pregnancy rates are higher. The risks vary among homeless persons for malnutrition, nutrition-related health problems, drug and alcohol abuse, and mental illness. For example, among homeless persons, fewer heads of families than single adults are substance abusers, and mental illness varies in prevalence among single men, single women, and parents in homeless families. Homeless persons need improved access to food, nutrition, and health services. More nutrition education needs to be available to them and to service providers. Use of representative samples and validation of self-reported nutrition and health data will help future investigators to clarify the relationships between the characteristics of the homeless and their nutritional status.