1. A study has been made of the reactions between polyvinyl alcohol and butyl vinyl and phenyl vinyl ethers, the proportions of components being varied. 2. It has been shown that reaction between polyvinyl alcohol and butyl vinyl or phenyl vinyl ether leads to the formation of polyacetals of polyvinyl alcohol. 3. It is possible that the formation of the polyacetals of polyvinyl alcohol passes through the stage of mixed acetals, which subsequently undergo cyclization.