Adamantinomas of long bones are rare primary malignant bone tumors. A case of a woman who died of pulmonary metastases of an adamantinoma of the tibia is presented. A unique feature of this case is the association with hypercalcemia. The association of hypercalcemia, hypophosphatemia, decreased parathyroid hormone levels and increased urinary cAMP excretion suggests a humorally mediated hypercalcemia. Histologic and ultrastructural analysis of the pulmonary metastases demonstrated that the tumor was composed of a heterogeneous cell population with mesenchymal and epithelial differentiation.