ObjectiveHypopharyngeal carcinoma is a common malignant tumor in head and neck ,    invasion and metastasis are responsible for the high death rate.    Recently studies indicate that cyclooxygenase-2 (COX-2)    is up-regulated in many kinds of malignancies . The aim of   this research is    to    investigate    the    expression    of   cyclooxygenase-2(COX-2) in hypopharyngeal carcinoma tissues and to study on the relationship between the expression of   cyclooxygenase-2 (COX-2) and clinical pathological characters in    hypopharyngeal carcinoma by immuno-histochemical method.MethodsThe expression of cyclooxygenase-2(COX-2) in hypopharyngeal carcinoma tissues of 40 cases and paraneoplastic hypopharyngeal normal mucosa of 15 cases was studied by immunohistochemical method,    and to    study    the    relationship    between    the    expression    of cyclooxygenase-2(COX-2) and clinical pathological characters.ResultsThe positive rate of cyclooxygenase-2(COX-2) expression in hypopharyngeal carcinoma tissues(67. 5 %) was significantly higher than