Polymeric biomaterials are synthetically derived or modified biological polymers designed for in vivo use or for use in the proximity of biological fluids. As is common in the polymer industry, these polymers are produced in bulk and then shaped for a specific end-us,e. Characterization of biopolymers has two purposes: 1. development of parameters for processing; 2. determination of end-use performance characteristics. In biorelevant testing of polymers, the temperature of interest is limited to 37 +/- 3 degreesC, and it is the time effects in aqueous environment containing biological molecules that are critical. Parameters that may serve to accelerate biopolymer response include sample surface area and the concentration of molecules present in the test environment. The development of biorelevant TA databases allows the rational correlation of biorelevant and conventional TA responses and offers an avenue for the development of accelerated aging evaluation procedures. Polymeric biomaterials, especially new compositions, are often tested for biocompatibility, bioerosion rate or cell growth specificity without regard to the morphological structures introduced during materials processing. It will be shown that in addition to the potential influence on biological response, processing induced structure profoundly influences materials properties under biorelevant conditions. Using a combinatorial library of polymeric, bioerodable compositions, these is:sues will be explored with emphasis on in vivo dimensional stability and mechanical property retention.