Sewage sludge, a mixture of solids and water produced during the treatment of waste water, can be used as a valuable fertiliser and is currently widely used as such in agriculture. Since 1981 a joint Forestry Commission/WRc research programme has evaluated the growth responses and environmental implications of sewage sludge applications to forests (Bayes et al., 1991). This programme has shown that tree growth can be significantly enhanced following sludge application (Wolstenholme et al., 1991; Dutch and Wolstenholme, in press). The experience gained from the various pilot trials and experiments has been used to develop the following guidelines for the use of sewage sludge in forestry. Research is continuing and future findings will be used to update the guidelines. Part I of the manual addresses the subject of the silvicultural value of sewage sludge as a forest fertiliser. This will assist the forest manager in selecting suitable sites where a growth response can be expected. Part II of the manual, the Code of Good Practice, deals with the practicalities of suitable application procedures and is aimed at those actively involved in these procedures, including forest managers and water industry staff.