Heteromorphism of Y chromosome was studied in head and neck cancer patients and leukemia patients. The results were compared with similar data obtained for healthy men. It was observed that, compared to the controls, mean lengths of Y chromosome were nonsignificantly higher for leukemia patients and lower for head and neck cancer patients. The euchromatic region of Y chromosome (Y-eu) remained comparable in the controls and the leukemia patients, whereas it was smaller in patients with head and neck malignancies. The heterochromatic region (Y-het) was more or less analogous in controls and head and neck cancer patients, however, it was significantly larger in patients with leukemia (P less than 0.02).