A 54-year-old male with chronic osteomyelitis presented with new-onset hypercalcemia. Extensive initial evaluation did not reveal the underlying cause of his hypercalcemia. Subsequent biopsies revealed squamous cell carcinoma transformation consistent with Marjolin's ulcer. Timely surgery had been shown to be effective in achieving remission in patients with Marjolin's ulcers, even in the presence of hypercalcemia. Therefore, we recommend that patients with chronic wounds and new-onset or otherwise unexplained hypercalcemia should be evaluated for development of Marjolin's ulcers.