A preliminary environmental classification of housing-related diseases in developing countries is presented. This groups these diseases into six categories: those related to defects in (1) buildings and the peridomestic environment, (2) water supply, (3) sanitation, (4) refuse storage and collection and (5) food storage and preparation; and (6) industry-related diseases resulting from housing location (close to polluting industries or on contaminated land) and from the use of the home as a workplace. Each category has three subcategories: communicable diseases (including zoonoses), non-communicable diseases, and mental illnesses and psychosocial disorders.