The article defines tracing paper, then gives a brief history of its manufacture (including some old recipes) and the uses to which it was put. The various forms of deterioration likely to be found with these papers are described and illustrated with photographs. Apart from intrinsic factors, tracing papers are also damaged by pigments/inks which may have been used on them, and by dirt and water from poor storage. Problems found when beginning the conservation/restoration of the 1,50 million items on tracing paper in the national maritime museum, london are described. Methods adopted for unfolding brittle paper, cleaning, removal of creases and old linings are described, then restoration techniques of relining, lamination, encapsulation. Finally a case history of the treatment of a ship's plan on tracing paper, using beva 371, is described. Advantages and disadvantages of every stage of the work are given, as well as additional information obtained from further trials. Recommendations for storage, bibliography, information on materials and suppliers. -- ICCROM