We present an infrared (IR) spectroscopic view of the pathological features of Alzheimer's disease (AD), along with a means of classifying the spectroscopic data nonsubjectively using several multivariate methods. The results demonstrate that IR spectroscopy can potentially be used in the diagnosis of AD from autopsy tissue. Although several spectral features that appear to be related to the disease process can be detected by a visual inspection of the IR spectra of AD grey matter, the appearance of these features was inconsistent. A more successful (consistent) diagnosis is achieved using multivariate analysis of the spectroscopic data. It is shown that correct classification of white and grey matter from brains identified by standard pathological methods as heavily, moderately, and minimally involved can be achieved with success rates of greater than 90% using appropriate methods. Classification of tissue as either control or AD was achieved with a success rate of 100%. © 1995 John Wiley & Sons, Inc.