Humoral hypercalcemic syndrome associated with tumors of the female reproductive system is believed to be uncommon, and only 27 such cases have been identified prior to 1980. We describe 2 patients with humoral hypercalcemia in clear cell adenocarcinoma of the uterus, and review the literature on previously published cases. Both our patients fulfilled the criteria for humoral hypercalcemic syndrome, namely: hypercalcemia without bone metastases ranging from 12.8 to 14.1 mg/dl in the presence of normal serum parathyroid hormone levels, reduced tubular reabsorption of phosphate, and reduced serum albumin. We propose that humoral hypercalcemia is perhaps not a rare complication of uterine malignancy and, that increased awareness may result in early diagnosis of this important metabolic problem.