White matter hyperintensities (WMH) are common in older brains. We analyzed how WMH affect white matter (WM) tracts and particularly their normal-appearing WM (NAWM). We used MRI of 52 participants (72.2±0.7y) to quantify diffusion parameters of WMH-affected tracts. The intersections of tracts with WMH were identified and volumes quantified. Diffusion parameters were measured for tract-WMH, tract-NAWM, and for tract-NAWM at different distances from the tract-WMH edge, and from the edge of nearby—non-intersecting—WMH. Tract-NAWM showed a gradient of diffusion abnormalities away from tract-WMH, and nearby-WMH. Tract-WMH diffusion, and either tract-WMH volume or whole-brain WMH load, predicted tract-NAWM diffusion.