Taking into account economic and environmental aspects, it can be assumed that the majority of packagings will be made of paper products in the future. Packaging paper grades require good strength properties. This can be obtained by paper production from primary material, to be precise from unbleached kraft pulp, most often based on softwood. To provide desired strength level to sack paper, some chemicals were used. Tests proved that addition of chemical agents in the production of sack paper brings satisfactory results enhancing its strength properties in this way. Synthetic agents showed better effectiveness then natural agents.