Total neuron numbers in the amygdala and in eight of its subnuclei were determined in 9 cases of Alzheimer's disease (AD) and in 6 age-matched controls (AMC). Total neuron numbers were obtained using the fractionator. A neuron loss of 56.3% for the left amygdala and 50.5% for the right amygdala in AD was found, being more severe than previously reported. The subdivisions showed a differential neuron loss ranging from 35.5% in nucleus lateralis of the right amygdala to 70.4% in the nucleus basalis accessorius of the right amygdala. Moreover, a shift in size distribution to smaller neurons could be demonstrated. No left-right hemispheric differences were detected in total neuron numbers in AD and AMC.