This invention relates to the use of certain finely divided, stable and relatively low viscosity dispersions of polyisocyanate polyaddition products in compounds having hyroxyl groups. The dispersions are produced by reacting1. organic polyisocyanates with2. compounds having primary and/or secondary amino groups and/or primary hydroxyl groups in3. compounds having at least one hydroxyl group, whereinCompounds (3) have secondary hydroxyl groups in cases when compounds (2) have primary hydroxyl groups and wherein the components are reacted in the presence of more than 4% by weight of water, based on the quantity of reaction mixture including water.