One characteristic feature of the aged central nervous system (CNS) is neuron loss. Programmed cell death (PCD) has been implicated in neuronal death during development and may be involved in a number of age-related neurodegenerative diseases of the CNS. Cell death in the aging cerebral cortex was investigated in the present morphometric and immunohistochemical study of rat frontal cortex by detection of bcl-2 as the factor preventing PCD. The results were interpreted in the light of the bioenergetic features of aged motoneuron cells. Our results showed that 1) bcl-2 does not influence neuronal survival, and ii) the presence in aging frontal cortex of minor cellular morphometric and bioenergetic modifications, confirming the difference between normal aging and neurodegenerative disease.