20 selected right-handed very healthy subjects (10 young adults and 10 presenile subjects mean age 28.3 and 59.6) were tested for CNV activity with a simple warned reaction time (RT) paradigm. EEG and CNV components (post-S1, N1, P2, P3; early CNV; N1200; late CNV; CNV resolution) were recorded from Fz, C3, Cz, C4, P3, Pz, and P4 referenced to linked mastoid electrodes. EOG, RT and stimuli were also recorded. The presenile group differed significantly from the younger group in the auditory post-S1 N1 and P3, and in the early (O-wave) and late (P-wave) CNV complex components. A progressive amplitude reduction only in frontal leads between O-wave and P-wave with the lowest point being reached in the P-wave was characteristic in the presenile group. Further, presenile subjects showed relatively flat CNV waveshapes of low amplitude and, as a whole, performed a little less well than young persons. This finding suggests that the statistically significant changes in post-S1 EPRs and CNV activity recorded in our presenile subjects, without appreciable deficits in behavioral and mental performance, could be alerting signs of early brain involutional processes related to minimal and subclinical decrement of orienting, attentiveness and response preparation capabilities. If such is the case and it could be confirmed in a larger sample of very healthy subjects, these age-related changes in the presenium could be of considerable practical importance for clinical and research applications.