Neuroimaging studies have shown structural and functional abnormalities in parts of the cortico-striato-thalamo-cortical (CSTC) brain circuitry in patients with obsessive-compulsive disorder (OCD). However, little is known about changes in the interhemispheric functional homotopy in the resting-state in OCD. This study used a voxel-mirrored homotopic connectivity (VMHC) approach combined with resting-state functional magnetic resonance imaging to investigate changes in interhemispheric functional homotopy in 60 OCD patients and 60 healthy controls. Compared with the healthy controls, the OCD patients showed decreased VMHC values in the thalamus. The results suggest that changes in functional homotopy in the CSTC circuitry may be involved in the pathophysiologic mechanism of OCD. Our findings provide new evidence of abnormalities in the CSTC circuitry in OCD.