Objective: There is emerging evidence that aberrations in the integrity of cerebral white matter tracts, especially those connected to limbic structures, play a role in the pathophysiology of schizophrenia. The fomix is the primary efferent neural pathway of the hippocampus and has been shown to be abnormal in adults with schizophrenia. Method: High-resolution structural magnetic resonance imaging and diffusion tensor images were obtained on 15 patients with childhood- and adolescent-onset schizophrenia and 15 age- and sex-matched controls. Measures of cross-sectional area and water diffusion properties were obtained on regions of interest of the fomix performed by a trained radiologist. Results: The volume of the fomix was significantly smaller (10.9%) in children and adolescents with schizophrenia compared to controls (Cohen d = 0.87, p = .025). There were no significant differences between the fractional anisotropy or mean diffusivity between the groups. Conclusions: These findings suggest that the early stages of schizophrenia are associated with a decrease in fomix volume without microstructural white matter changes. The volume differences may reflect an early insult to neighboring brain regions (i.e., hippocampus), that could decrease the number of efferent fibers without necessarily disrupting fiber integrity. © 2008 by the American Academy of Child and Adolescent Psychiatry.