Hydrolytic degradation of an aliphatic polyacetamidine at different pH values was studied using H-1 NMR spectroscopy. It could be shown that degradation occurred at neutral and basic conditions whereas under acidic conditions the polyamidine was stable. In the course of degradation, aliphatic acetamide, amine and acetic acid are formed. The ability of the polyamidine to release active compounds bonded ionically to the polymer backbone by hydrolytic decomposition was studied by UV spectroscopy. The measurements were performed on a mixture of the polyamidine and salicylic acid as an example. The release behavior of a 1:0.8 mixture at pH 7 was nearly linear within the first 10 h and went to completion after 30 It. This system is discussed with respect to the development of new drug delivery systems based on polyamidines. (C) 2004 Elsevier Ltd. All rights reserved.