Uniform polymers are characterised by a narrow molecular weight distribution (MWD). Uniformity is also defined bychemical
structure in respect of (1) monomer orientation, sequence and stereo-regularity, (2) polymer shape and morphologyand (3) chemical functionality. The function of natural polymers such as polypeptides and polynucleotides is related to theirconformational structure (e.g. folded tertiary structure). This is only possible because of their high degree of uniformity. Whilecompletely uniform synthetic polymers are rare, polymers with broad structure and MWD are widely used in medicine and thebiomedical sciences. They are integral components in final dosage forms, drug delivery systems (DDS) and in implantabledevices. Increasingly uniform polymers are being used to develop more complex medicines (e.g. delivery of biopharmaceuticals,enhanced formulations or DDS''s for existing actives). In addition to the function imparted by any new polymer itwill be required to meet stringent specifications in terms of cost containment, scalability, biocompatibility and performance.Synthetic polymers with therapeutic activity are also being developed to exploit their polyvalent properties, which is notpossible with low molecular weight molecules. There is need to utilise uniform polymers for applications where the polymermay interact with the systemic circulation, tissues or cellular environment. There are also potential applications (e.g. stimuliresponsive coatings) where uniform polymers may be used for their more defined property profile. While it is not yet practicalto prepare synthetic polymers to the same high degree of uniformity as proteins, nature also effectively utilises many polymerswith lower degrees of uniformity (e.g. polysaccharides, poly(amino acids), polyhydroxyalkanoates). In recent years it hasbecome possible to prepare with practical experimental protocols sufficient quantities of polymers that display many aspects ofuniformity. This review describes practical strategies for polymer synthesis focusing on addition processes that have beendeveloped that allow narrow MWD polymers to be prepared. Also described are some examples where aspects of polymeruniformity in terms of molecular weight and/or chemical constitution are exploited for their unique properties.