The rate of enzymatic ATP synthesis is shown to depend on the zinc isotopes. The ATP producing activities of creatine kinase and pyruvate kinase in which Zn2+ ions have magnetic nuclei 67Zn are found to be 2-6 times higher than that of enzymes in which Zn2+ ions have nonmagnetic nuclei 64Zn. The isolated rat heart muscle mitochondria exhibit a similar effect. An expression of this magnetic isotope effect in enzymatic ATP synthesis processed in the presence of Zn2+ ions is in a favor to the ion-radical mechanism of ATP production occurred within a high zinc concentration range. Both fundamental aspect and a possible pharmacological significance of the phenomenon described are under discussion.