Hypercalcemia is a common and potentially life-threatening metabolic derangement associated with many malignancies, especially solid tumors and multiple myeloma. Hypercalcemia has been reported only rarely with acute myelogenous leukemia. We describe a patient who developed hypercalcemia in association with transformation of agnogenic myeloid metaplasia into M7 acute myelogenous leukemia. Laboratory investigation revealed low levels of serum parathyroid hormone, undetectable levels of parathyroid hormone-related peptide, and normal levels of 25-hydroxyvitamin D. These observations suggest that another mediator was responsible for hypercalcemia in this patient. Awareness of this rare complication of acute myelogenous leukemia is essential for prompt diagnosis and management.