The condition of forests in the United Kingdom is monitored through two projects undertaken by the Forestry Commission. The first, referred to throughout this publication as the long-term monitoring project, was started in 1984. It was developed in response to a growing concern that air pollution might be affecting the condition of trees in Britain. The second project, referred to as the European Community (EC) forest health inventory, was started in 1987 as a direct result of European Community legislation (Commission Regulation (EEC) No. 1696/87). The results of both projects are presented separately in this Bulletin. The majority of the Bulletin is concerned with the longterm monitoring project; results from the EC forest health inventory are summarised towards the end.