The present study evaluated the validity of visual rating of medial temporal lobe atrophy on coronal magnetic resonance imaging scans in a population of demented and non-demented individuals. Medial temporal lobe atrophy in 194 subjects was visually rated from hard copies, using a 0-4 rating scale, and a comparison was made with the absolute volumes (ccm) of the medial temporal lobe as estimated with volumetry, using a stereological method. We found a highly significant correlation between the estimated and stereologically measured volumes. There was a 10-fold difference in time spent on rating medial temporal lobe atrophy (1-2 min) vs. time spent calculating the medial temporal lobe volume (10-12 min) on a single subject. The diagnostic accuracy of both methods showed that visual rating was more efficient than volumetry in differentiating Alzheimer's disease from control subjects, We conclude that visual rating is a reliable and fast method to estimate medial temporal lobe atrophy in demented subjects in a clinical setting. Copyright (C) 1999 Elsevier Science Ireland Ltd.