It is known that malignant tumors occasionally produce hormone-like substances. However, they rarely produce two or more kinds of hormonal factors simultaneously. We describe the clinical, biochemical, and immunohistochemical findings in a patient with squamous cell carcinoma of the larynx associated with leukocytosis and hypercalcemia, without bone metastasis. The serum granulocyte colony-stimulating factor (G-CSF) level was 222 pg/ml (normal, < 38 pg/ml), and decreased to 15 pg/ml after surgery. The serum parathyroid hormone-related protein (PTHrP) level was 5.6 pmol/l (normal, < 0.5 pmol/l), and this also decreased, to less than 0.5 pmol/l. G-CSF and PTHrP increased again with tumor recurrence. The production of G-CSF from the tumor was confirmed by immunohistochemical staining with monoclonal antibody against human recombinant G-CSF. The tumor was revealed to produce both G-CSF and PTHrP. In this article, we describe this very rare case of primary squamous cell carcinoma of the head and neck with the simultaneous ectopic production of more than one hormone-like substance.