Beryllium, being a bivalent metal, enters into competitive interrelations with the ions of other bivalent metals that are natural enzyme activators (magnesium, calcium, manganese, and others), while, at the same time, depressing their activity. This is why the study of the status of those electrolytes that can be beryllium antagonists among persons in contact with its compounds has taken on such great importance. Earlier research on magnesium and calcium metabolism among those stricken with berylliosis and who broke off their contact with the toxic substance several years ago showed a disarrangement in the relationship between these electrolytes. Also observed was a reduction in the magnesium level in the blood (plasma and erythrocytes), together with a tendency to its increased excretion with the urine and simultaneously an increase in the calcium content in the blood serum and a decrease in its excretion.