The oxalate tolerance test was performed in normal, thyroparathyroidectomized, vagotomized and atropinized dogs. Plasma or serum samples were obtained to determine the total calcium content before, immediately after, and up to 6 hr following a 30-min infusion of 40 mg/kg 0.4% sodium oxalate solution in physiologic saline. The recovery was significantly faster in dogs bilaterally vagotomized than in intact animals. Similarly accelerated recovery was also observed in animals in which one of the 3 groups of original rootlets of the accessory nerve (AH rootlets of Okinaka), which later joins the vagus, was bilaterally sectioned intracranially immediately after departure from the medulla oblongata. Administration of atropine during the test period also resulted in an accelerated recovery. In thyroparathyroidectomized, thyroparathyroidectomized-vagotomized and thyroparathyroidectomizedatropinized dogs the recovery apparently was retarded.