20%-ethanol was provided to adult female rats since a pregestational stage until weaning of the pups, and percentage proportion of thin, mushroom-shaped, stubby, or wide spines from the apical dendrite of hippocampal CA1 pyramidal cells, was counted at 15, 21, 40, and 90 days of age. By-kind-of-spine analysis revealed higher fluctuation of experimental spines, and less percentage of thin spines was observed in the ethanol-intoxicated rats concomitantly with a higher proportion of stubby or wide spines; through development. Because thin spines may propagate the synaptic potentials more efficiently than stubby or wide spines, this findings suggest that the electrical excitability and thereafter the firing pattern of those cells may be altered, due to the toxic effects of chronic ethanol ingestion.