Presenting Author details:nsegarra@clinic.ub.es Villarroel 170, 6,9, 08036 Barcelona, Spain, Tel.: +34 932275420. Background: While executive dysfunctions are very prevalent in schizophrenia they have traditionally been related only to frontal lobe integrity. The involvement of the cerebellum in schizophrenia has been documented in anatomical post-mortem, functional and volumetric neuroimaging studies, although the results are contradictory. Its possible role with respect to executive impairment in schizophrenia remains unclear. This study aims to establish the relationship between structural changes in the cerebellum and executive dysfunction in patients with schizophrenia using the voxel-based morphometry technique. Methods: We compared 28 outpatients with clinically stable schizophrenia (paranoid subtype) with 33 healthy controls. A widely used executive battery and the VBM approach were employed to investigate possible structural cerebellum changes on MRI. Results: Patients performed significantly worse on executive assessments and showed less symmetric and bilateral grey matter volume in both cerebellar hemispheres and vermis. Only in the schizophrenic group was an impairment in mental flexibility correlated with reductions in white matter volume in both symmetric and bilateral cerebellar hemispheres (r=−0.759 p<0.0001). Conclusions: This new evidence supports a role for cerebellar circuitry in mental flexibility, one of the executive dysfunctions observed in schizophrenia.