Hypocalcemia is an uncommon clinical symptom of patients with malignant tumors, and a number of factors may be involved in its development. The present study describes the case of a 67-year-old Caucasian female, presenting with severe refractory hypocalcemia and heart failure. The patient was subsequently diagnosed with breast cancer and bone metastases. The paraneoplastic origin of the syndrome was confirmed by its complete resolution once the tumor responded to specific antineoplastic treatments, comprising weekly paclitaxel and aromatase inhibitor administration. The present case report suggested the need for greater awareness of the possibility of paraneoplastic hypocalcemia in breast cancer patients, and suggested that this condition may also contribute to the occurrence of heart failure. The mechanisms potentially responsible for this event were discussed and a brief review of the literature presented.