Abstract: A packaging laminate comprising a rigid, but foldable paper or paperboard layer which has, at least on its one side, an outer film or coating of a water-insoluble polysaccharide compound which imparts to the packaging laminate tightness properties against liquid and water vapor and good sealing properties. Preferably, the other side of the core layer also has an outer film or coating of said polysaccharide compound. The polysaccharide compound in the two outer films or coatings contains a first water-soluble polysaccharide of polyanionic character and a second water-soluble polysaccharide of polycationic character, these being chemically or otherwise bonded to one another to form the water-insoluble polysaccharide compound. One preferred such polysaccharide compound may, for example, consist of a chemical compound or a chemical complex of chitosan and agar.