Radiosensitization efficacy of gold nanoparticles (AuNPs) with low energy radiations (88keV) was evaluated in vitro and in vivo on rats bearing glioma. In vitro, a significant dose-enhancement factor was measured by clonogenic assays after irradiation with synchrotron radiation of F98 glioma cells in presence of AuNPs (1.9 and 15nm in diameter). In vivo, 1.9nm nanoparticles were found to be toxic following intracerebral delivery in rats bearing glioma, whether no toxicity was observed using 15nm nanoparticles at the same concentration (50mg/mL). The therapeutic efficacy of gold photoactivation was determined by irradiating the animals after intracerebral infusion of AuNPs. Survival of rats that had received the combination of treatments (AuNPs: 50mg/mL, 15Gy) was significantly increased in comparison with the survival of rats that had received irradiation alone. In conclusion, this experimental approach is promising and further studies are foreseen for improving its therapeutic efficacy.