BACKGROUND Pamidronate disodium, a bone resorption inhibitor through osteoclast mediation, has been used to treat chronic hypercalcemia secondary to malignancy and chronic renal failure. We report the use of pamidronate for acute, severe hypercalcemia secondary to iatrogenic vitamin D poisoning. METHODS A 77-year-old female nursing home resident was inadvertently administered 50,000 units of oral vitamin D daily for 6 days. The patient presented with lethargy, abdominal pain, and vomiting. The patient's initial serum calcium concentration was 5.25 mmol/L (21 mg/dL). The patient was initially treated with hydration and furosemide but developed congestive heart failure. Pamidronate was used and calcium concentrations normalized by 24 hours after treatment. CONCLUSIONS We report a case of the use of pamidronate for significant hypercalcemia secondary to acute vitamin D poisoning. Although evidence of congestive heart failure was evident, dialysis was avoided without significant sequelae. Pamidronate therapy should be considered in patients with hypercalcemia secondary to acute vitamin D poisoning.