A consecutive series of 79 patients with probable Alzheimer's disease were assessed with a structured psychiatric evaluation, and diagnoses of apathy and depression were made using standardized criteria. Three-dimensional MRI scans were obtained from all patients, and images were segmented into gray matter, white matter, and CSF. White matter hyperintensities were edited on segmented images, and lobar assignments (frontal, temporal, parietal, and occipital) were made based on Talairach coordinates. Patients with apathy showed a significantly larger volume of frontal white matter hyperintensities than patients without apathy. Patients with depression had a significantly larger volume of right parietal white matter hyperintensities than patients without depression. However, neither apathy nor depression was significantly associated with lobar gray or white matter atrophy. Frontal and right parietal white matter hyperintensities are the strongest brain structural correlates of apathy and depression in Alzheimer's disease.