Introduction: Paclitaxel, a microtubule binding agent with potent anti-glioma activity in vitro, exhibits poor penetrance to the CNS when delivered systemically. To minimize toxicity and reach therapeutic concentrations in the CNS, paclitaxel was previously incorporated into biodegradable microspheres (Paclimer®), and the efficacy of Paclimer® was determined in a rat model of malignant glioma. In this study we report the safety of intracranial Paclimer® in a canine dose escalation toxicity study to prepare its translation into clinical scenarios.