The amount of intraneuronal lipofuscin in the parietal cortex and in the inferior olivary nucleus was measured in post-mortem tissue affected by Alzheimer dementia and in specimens from non-demented individuals. The results indicate that there is a liner relationship between the accumulation of cell body lipofuscin and advancing age, both in neuronal populations of the non-demented groups, and in the olivary neurones of the demented group. However, in the demented group, the lipofuscin fluorescence intensity of the parietal neurons was not significantly correlated with age. The estimated amount of lipofuscin in the olivary neurons in the demented group was significantly higher than in the non-demented group, when age has been taken into account (P less than 0.01). The possible pathogenic role of lipofuscin accumulation in ageing and Alzheimer dementia is discussed.