Children treated with cranial irradiation for brain tumors have reduced white matter volume and deficits in reading ability. This study prospectively examined the relationship between reading and white matter integrity within this patient group. Patients (n = 54) were treated with post-surgical radiation followed by 4 cycles of high-dose chemotherapy with stem cell support. At 12 months post-diagnosis, all patients completed a neuropsychology evaluation and a diffusion tensor imaging (DTI) exam. White matter integrity was determined through measures of fractional anisotropy (FA). Significant group differences in FA were found between above average readers and below average readers within the left and right posterior limb of the internal capsule, and right knee of the internal capsule with a trend within the left temporaloccipital region. The integrity of the white matter in these regions may affect communication among visual, auditory, and language cortical areas that are engaged during reading.