The objective of the present study was to assess the sub-chronic effect of combination between ethephon and gibberellic acid on brain mitochondrial adenosine tri-phosphatas, brain and whole blood acetyl cholinesterase. Male ICR (CD-1) mouse was used as an experimental model. The experiment duration was 23 weeks through which animals received diets containing ethephon in a series of concentrations of 0, 25, 50 and 75 milligram per kilogram diet respectively with and without 50 mg of gibberellic acid.  A significant variation was recorded between the effect of ethephon and that of ethephon - gibberellic acid combination on the activity of total mitochondrial ATPase in mice brain (P ≤ 0.05). Gibberellic acid antagonized the inhibition occurred by ethephon in case of the two smaller dietary concentrations 25 and 50 mg / kg diet. Ethephon induced a highly significant (p ≤ 0.01) concentration-dependent activation in Mg⁺² ATPase in animals exposed to the two lower dietary concentrations 25 and 50 mg / kg with and without gibberellic acid. Ethephon induced a highly significant (p ≤ 0.01) dietary concentration-dependent inhibition in brain Na⁺/ K⁺ ATPase. Gibberellic acid obviously reduced inhibition in animals received the two smaller concentrations (25 and 50 mg / kg diet). No significant variation was found in brain acetyl cholinesterase neither among treated groups nor between these groups and the control (p ≥ 0.05). Gibberellic acid induced a highly significant recovery in the inhibited whole blood AChE in groups fed the low concentrations of 25 and 50 mg / kg diet (p ≤ 0.01). While at higher concentration (75 mg / kg diet) gibberellic acid showed an additive inhibitory effect on whole blood AChE.