By means of the [14C]-2-deoxyglucose method the local cerebral glucose utilization (LCGU) was measured in 41 brain regions in autoimmune New Zealand Black (NZB) mice and in Carworth Farm Winkelmann (CFW) mice, which served as the control strain. At the age of 6 months, the mean LCGU of all measured areas and brain stem nuclei was 67.7 mumol glucose/(100 g x min) in the nonautoimmune CFW mice. These LCGU values are within the limits published by other observers. In contrast, in the aged-matched NZB mice the glucose use was markedly reduced, the mean LCGU of all measured areas being 37.7 mumol glucose/(100 g x min). These findings suggest that the immunological, morphological and behavioural abnormalities in the aged NZB mouse correlate with a reduced functional activity of the central nervous system, measured as reduced cerebral glucose utilization.