The report summarizes information on indoor pollution by formaldehyde (HCHO) in European countries participating in the concerted action "Indoor Air Quality and Its Impact on Man" (COST project 613). Major scope of the report is to give concise information to people involved in research planning, policy making and regulatory activities and to identify a European view of the issue. The summary includes a short review of health effects of formaldehyde, of existing air quality guidelines and standards and of indoor sources of formaldehyde. For those countries for which information has been made available occurring indoor concentrations and national policies have been collated. Preventive measures are briefly discussed unresolved problems are identified.