The methods applied up to now do not allow to define the border between the tumor and healthy tissue especially in advanced cases. Microlaryngoscopy facilitates the evaluation of the infiltration superficially, but does not allow for estimation its deeper penetration. CT and MRI often do not answer the question concerning the tumor spread as well. That is why the monoclonal antibodies marked with isotopes directed against specific antibodies of different neoplasms are applied in diagnostic. In the neoplasm development the great role play endopeptidases. They degrade the intercellular matrix and basement membrane and by this way made possible the neoplasm invasion. The high level of the endopeptidase in patients with neoplasm is a bad prognosis. The disposition of endopeptidase in neoplasm tissue is characteristic and gives opportunity to localise the border of healthy tissue thanks their inhibitors application. The inhibitor of cysteine endopeptidase obtained from hen egg and marked by J 125 was used in our study. The reaction between the cysteine endopeptidase inhibitor and malignant cells received directly from patients with tongue and laryngeal carcinoma and cells cultivated in vitro from the carcinoma.