Background: The role of the striatum in language remains poorly understood. I ntraoperative electrical stimulation during surgery for tumours involving the ca udate nucleus or putamen in the dominant hemisphere might be illuminating. Objec tives: To study the role of these structures in language, with the aim of avoidi ng postoperative definitive aphasia. Methods: 11 patients with cortico- subcort ical low grade gliomas were operated on while awake, and striatal functional map ping was done. Intraoperative direct electrical stimulation was used while the p atients carried out motor and naming tasks during the resection. Results: In fiv e cases of glioma involving the dominant putamen, stimulations induced anarthria , while in six cases of glioma involving the dominant caudate, stimulations elic ited perseveration. There was no motor effect. The striatum was systematically p reserved. Postoperatively, all patients except one had transient dysphasia which resolved within three months. Conclusions: There appear to be two separate basa l ganglia systems in language, one mediated by the putamen which might have a mo tor role, and one by the caudate which might have a role in cognitive control. T hese findings could have implications for surgical strategy in lesions involving the dominant striatum. Background: The role of the striatum in language remains poorly understood. I ntraoperative electrical stimulation during surgery for tumors involving the ca udate nucleus or putamen in the dominant hemisphere might be illuminating. Objec tives: To study the role of these structures in language, with the aim of avoidi ng postoperative definitive aphasia. Methods: 11 patients with cortico-subcortical low grade gliomas were operated on while awake, and striatal functional map ping was done. Intraoperative direct electrical stimulation was used while the p atients carried out motor and naming tasks during the resection. Results: In fiv e cases of glioma involving the dominant putamen, stimulations induced anarthria, while in six cases of glioma involving the dominant caudate, stimulations elic ited perseveration. There was no motor effect. The striatum was systematically p reserved Postoperatively, all patients except one had transient dysphasia which resolved within three months. Co nclusions: There appear to be two separate basa l ganglia systems in language, one mediated by the putamen which might have a mo tor role, and one by the caudate which might have a role in cognitive control. T hese findings could have implications for surgical strategy in lesions involving the dominant striatum