The application of ploymers in biological systems has become an important feature of medical care. They have been most commonly used for implants and prosthetic devices; however, recent interest has developed to use polymers as drugs or drug delivery systems. Polymeric drugs were the first to receive attention, and now the primary interest focuses on new modes of drug administration. The present paper deals with description of the polyanionic polymers (synthesis, characterisation and biocompatibility). Research in this area is highly interdisciplinary and involves not only polymer chemists but health scientists and physicians.