The C-13-n.m.r. signals were assigned to the composing structural groups of the copolymers. The composition of the copolymers was determined by C-13 n.m.r. using the NOE extinction technique. The analyzed samples were synthesized under normal and relatively mild reaction conditions. Despite this and purification methods that avoided elevated temperatures, it was not possible to find hemiformal groups in any amount. Therefore it is possible to analyze these copolymers composed of formal, vinylacetate and vinylalcohol structural groups in a relatively easy way by means H-1 n.m.r.