Introduction: Cerebellar mutism syndrome refers to the muteness (lack of speech) that follows lesions of the cerebellum. It’s characterized by a late onset, limited duration, and in some cases long-term language sequelae. Its pathogenesis it s not clear yet, but it has been attributed a role to a damage of the dentate nucleus and of the dento-rubro-thalamic tract. Objectives: Identify potential risk factors (clinical or anatomical) to predict the onset of cerebellar mutism after posterior fossa surgery Compare, using MRI analysis and DTI tractography, the integrity of the dento-rubro-thalamic tract in patients with and without cerebellar mutism. Methods: Prospective follow up study of patients operated of posterior fossa tumors between November 2012 and 2013. We performed a study with DTI of the dento rubro thalamic tract in pacients with and without postoperative mutism. Results: 53 patients under the diagnosis of posterior fossa tumor underwent surgical resection. 5 pacients presented postoperative mutism (9,4%). There was a significant association between postoperative medulloblastoma diagnosis and postoperative mutism. Tumor volume was not significant. The volume of left and right dento rubro thalamic tract were significantly lower in patients with cerebellar mutism. The fractional anisotropy of the right superior cerebellar peduncle was also lower in patients with postoperative mutism. Conclusions: The postoperative cerebellar mutism is a relevant complication after a posterior fossa surgery. Our study supports the role of dento rubro thalamic tract damage in the pathogenesis of this syndrome. Special care must be taken during surgery to prevent damage to this tract.