Synthetic bioabsorbable polymers, first developed in the 1960s, are being increasingly used in the manufacture of medical devices. Some of the uses these devices have been applied to are suturing, orthopaedic fixation and drug-delivery. The principal advantage offered by bioabsorbable polymers is that a device made from these materials does not require removal. However, the degradation characteristics of these materials occasionally cause problems in medical uses, such as negative tissue reactions and poor wound healing. Therefore, a need exists to develop techniques which can modify the degradation characteristics ofbioabsorbable polymers. This study investigated the application of high-energy radiation, in the form of gamma and electron-beam (e-beam) radiation, to the bioabsorbable polymers polylactide (PLA) and polylactide-co-glycolide (pLGA). It was fqund that both forms of radiation reduce the molecular weight of these polymers in proportion to the delivered dose. Additionally, it was found that the effect of e-beam radiation is depth-dependent, with the surface material being more significantly affected than the core material. The reduction in the molecular weight ofthe bioabsorbable materials was found to have led to reduced mechanical strength and absorption time. After e-beam irradiation these characteristics were also found to be depth-dependent The work presented in this thesis suggests that e-beam radiation can be used to tailor the characteristics ofa bioabsorbable polymer that are crucial to its use in medical devices. This tailoring can be location specific, which it is believed will lead to the production ofbioabsorbable medical devices with improved efficacy and less negative response.