Context: There is increasing evidence that schizophrenia is characterized by abnormalities in white matter. Objective: To investigate the integrity of white matter tracts in adolescents with schizophrenia. Design: Cross-sectional, case-control, whole-brain, voxel-based analysis and fiber tractography using diffusion tensor magnetic resonance imaging. Setting: University research institute. Participants: Forty-four individuals (age range, 11-18 years), 23 with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder and 21 demographically similar healthy controls. Main Outcome Measures: Fractional anisotropy, trace, and radial diffusivity of diffusion tensor and quantitative tractography. Results: Voxelwise analysis revealed that adolescents with schizophrenia had reduced fractional anisotropy within the left inferior temporal (P <.001) and occipital (P <.001) regions. Tractography was performed to extract the left and the right inferior longitudinal fasciculi (ILF). Measuring the mean diffusion indices along the left ILF, patients had significantly reduced fractional anisotropy (P <.001) as well as significantly increased radial diffusivity (P <.001) and trace (P=.003) after adjusting for differences in a measure thought to reflect premorbid intelligence, Wide Range Achievement Test 3 reading scores. Exploratory analyses revealed that patients with a history of visual hallucinations had lower fractional anisotropy in the left ILF (P=.02) than patients without visual hallucinations. Conclusion: Our findings, which benefited from greater image resolution and methodological control than previous studies conducted in adolescents with schizophrenia, provide strong evidence for lower white matter integrity in the left ILF, particularly for patients with a history of visual hallucinations.