Hypercalcemia presenting in ovarian cancer is uncommon in the clinic.Here, two cases of ovarian epithelial carcinoma that presented with severe hypercalcemia were reported, with a review of the literature.The laboratory findings and stepwise clinical investigations of these two cases differed, indicating distinct underlying causes of hypercalcemia.In case one, the serum levels and immunostaining for parathyroid hormone-related protein (PTHr P) verified humoral hypercalcemia of malignancy (HHM).In case two, the high level of parathyroid hormone (PTH) and the scintigraphy scan showing parathyroid gland adenoma confirmed primary hyperparathyroidism-induced hypercalcemia.Both patients received optimal cytoreductive operation and adjuvant chemotherapy but showed different outcomes respectively.This article focused on differential diagnosis of ovarian cancerassociated hypercalcemia, by stepwise imaging and laboratory investigation, and the appropriate therapy should be considered based on the different etiologies.