Crude and corrected amygdaloid volumes were computed from magnetic resonance scans in ten patients with frontotemporal dementia (FTD), 25 patients with Alzheimer's disease (AD) and 27 controls. Amygdaloid atrophy was present in FTD (P<0.005) compared to controls, and a trend for increasing atrophy from controls, through FTD to AD (P for trend <0.00005) showed that FTD amygdaloid volumes were intermediate between controls and AD. Behavioral and Klüver-Bucy-like symptoms, characteristic of FTD, cannot be explained by amygdaloid atrophy alone.