Dioscorea tokoro has long been used in Korean traditional medicine as a pain killer and anti-inflammatory agent. A 53-year-old male who consumed water that had been boiled with raw tubers of D. tokoro as tea presented with numbness and spasm of both hands and feet. Laboratory results showed hypocalcemia, hypoparathyroidism, and vitamin D insufficiency. During his hospital stay, colitis, acute kidney injury, and toxic encephalopathy developed. The patient received calcium gluconate intravenous infusion and oral calcium carbonate with alfacalcidol. His symptoms improved gradually, but hypocalcemia persisted despite the calcium supplementation. We suggest that ingestion of inappropriately prepared D. tokoro can cause symptomatic hypocalcemia in patients with unbalanced calcium homeostasis.