In Sweden there are around 2,800 single figures, shrines and crucifixes as well as around 600 winged altar pieces from the Middle Ages; most of them are scattered over the country in the churches. The number of problems which arise from the preservation of this big cultural heritage is discussed. The importance of scientific examination of the objects and a knowledge of the original materials and techniques is stressed for the development and choice of the right conservation method. Methods must take into consideration the nuances of the surface which determines the character of medieval polychrome objects of art.