A review of 208 cases of surgically treated squamous cell carcinoma of the esophagus revealed 16 (7.7%) with hypercalcemia. There was no evidence of bone metastases in 13 (6.3%) of the patients with hypercalcemia. Pathogenesis of this hypercalcemia without bone metastases was suggested to be multifactorial. Anastomotic leakage and malnutrition because of fasting were the most possible causes of mild hypercalcemia, and moderate to severe hypercalcemia was thought to be due to subclinical and clinical recurrence of the tumor, probably with PTH-like hormonal activity. Overall survival rates in the groups with and without hypercalcemia were 18.2 and 61.7% at the 12th postoperative month and 9.1 and 37.8% at the 24th month, respectively. Thus hypercalcemia is a significant prognostic factor linked to an unfavorable clinical course even in patients with no evidence of bone metastases.