The objective of this study is is the evaluation of the long-term consequences on the psycho-motor growth and development of children treated for severe dehydratation caused by diarrhoea in the early infancy.As electrophysiological measurements, we used EEG and EXG. Electroexpectogram (EXG) is a method we introduced earlier (Bozinovska et al., 1992) as an extension of the classical CNV paradigm. It is a paradigm where S2 signal is computer controlled, in such a way that each time CNV appearance is recognized, S2 is turned off, and each time CNV extinction is recognized, S2 is turned on again. The observed oscillatory process is subject dependent.In this study we examined 39 children of mean age 8.82 years, treated for dehydratation in their early infancy. We observed that the number of CNV onsets in the EXG trace (mean 3.5 onsets in the control group and 0.6 onsets in the examination group) and the maximal amplitude of the CNV signal (mean 13.8 μV for control and 8.9 μV for examination group), is significantly smaller in the group of treated children comparable to the control group of healthy children. Also, the reaction time is prolonged in the examined group (245 ms versus 303 ms). Parameters of other psychological tests (Kohs Block-Design test, Gestalt Bender motor test, Rey's test) confirm the significant differences between the control and the examined group.