White matter lesions (WML) and hippocampal atrophy (HA) on MRI commonly co-occur in Alzheimer's disease (AD) and are thought to play a role in the etiology of AD. It is still not known whether WML and HA are independent or related. The authors investigated the relation between WML and HA in 179 patients with probable AD who had a cerebral MRI. A linear relation was found between WML and HA, especially for WML in the frontal and parieto-occipital regions. The results suggest that vascular pathology and typical AD pathology (HA) are related.