Definition of the boundaries of primary tumor is the basis of pre-therapeutic analysis. The uncovered obscure spreading may cause failure of therapy. The retrospective study of the group of 69 patients with larynx cancer analyzed distribution of the tumor occurrence in individual localities and sub-localities of larynx, evaluated endolaryngeal and extralaryngeal spreading of the tumor, and followed up the error of clinical finding on the basis of comparing categories T and pT. The examination revealed significant mutual endolaryngeal spreading between glottic and supra-glottic region and a high proportion of transglottic tumors. The anterior commisure, subglottic, preepiglottic and paraglottic space represent critical regions of larynx, which must be carefully evaluated the operation. These areas also include transglottic space, the area of arytenoid cartilage in glottic tumors and radix of lingua in supraglottic tumors. The agreement of the preoperation T and the histopathological pT findings in larynx was observed in 83% of cases. The planning of the extent of operation in partial as well as in total laryngectomies based on the TNM classification is risky, and possible ways of local spreading of larynx tumor should be assessed and the results of preoperation examination correctly interprete

        Key words: larynx tumors, local spreading, correlation of T and pT