The development and implementation of immunohistochemical methods have revolutionized the practice of surgical pathology over the past four decades. This phenomenon has occurred because of the development of an extensive array polyclonal antisera and monoclonal antibodies together with increasingly more sensitive immunological stain sequences and detection methods. Immunohistochemistry has become an essential part in pathology both in the facilitation of cell recognition in circumstances where the diagnosis is uncertain based upon hematoxylin and eosin stain alone and in helping to determine the biologic potential of tumors. Knowing the principles and practice of applied immunohistochemistry makes the pathologist more competent and effective through greater understanding of tumor differentiation and classification. In the future, the pathologist will continue to play a central role in diagnosis and immunohistochemistry as the routine armamentarium in diagnostic tests.Thus, these changes likely will improve the understanding of diseases that affect the head and neck and the ability of the pathologist to render correct diagnosis.