We present two pediatric cases demonstrating that diffusion tensor imaging is more efficient at revealing microstructural abnormalities of the brain than conventional magnetic resonance imaging because it enables measurements of the directionality and integrity of white matter fiber tracts. One patient suffered from left hemiparesis, and the other had right hemiparesis. However, whereas conventional magnetic resonance imaging showed only the findings of traumatic contusional hemorrhages in the left temporal and parietal lobes of the first patient and focal encephalomalacia in the left anterior thalamus of the second patient, diffusion tensor imaging successfully disclosed microstructural abnormalities in the right cerebral peduncle of the midbrain of the first patient and in the posterior limb of the left internal capsule of the second. Theses two cases demonstrate that diffusion tensor imaging is more capable than magnetic resonance imaging at detecting the microstructural pathologic lesions that are responsible for clinical motor weakness, especially when conventional magnetic resonance imaging has failed to detect subtle structural abnormalities.