PURPOSE: Currently, there is no conclusive treatment for brainstem tumor. To facilitate the development of new treatments, it is essential to establish predictive preclinical in vivo models in which therapeutic modalities can be evaluated. Although a few rodent models have been reported, there is no novel approach that can monitor tumor response qualitatively and quantitatively. MATERIALS AND METHODS: Bioluminescence imaging was used to characterize a rat brainstem tumor model. In this model, 9L gliosarcoma cells, transduced with an onco-retroviral vector containing the luciferase coding sequence, were inoculated into Fisher 344 rats. RESULT: Histopathological assessment showed successful cell implantation into the brainstem. There was a strong correlation between pathological tumor volume and luminescence strength. Longitudinal quantitative responses of the tumor after application of a therapeutic agent were also demonstrated. CONCLUSION: This study demonstrates a robust rodent model with the ability to monitor brainstem tumor growth and response to chemotherapeutic agents.