Among patients exposed to hydrofluoric acid the potentially lethal effect of calcium depletion induced by binding with fluoride ion has not been well reported. Three patients exposed to hydrofluoric acid had acute fluoride poisoning with serum calcium levels equal to or below 4.1 mgm/dl. Treatment included administration of large amounts of calcium, both intravenously and by subsechar injection, to replenish the biologically active calcium and to bind fluoride. This report describes successful treatment of two survivors, apparently the first two, of severe hypocalcemia caused by hydrofluoric acid.