Sažetak Root canals o f both vital and non-vital teeth are filled with a content which should be removed prior to their filling with artificial materials. This content consists o f vital pulp, predentin, decomposed pulp, microorganisms, toxins, proteolythic enzymes and debris. Sole instrumentation o f the root canal is inadequate for its thorough cleansing and disinfection during endodontic treatment. Thus, instrumentation should be combined with chemical treatment for the procedure to be fully successful. Liquids for chemical treatment o f the root canal remove the content by physical washing, decomposition o f organic compounds and dissolution o f inorganic components, whereas the number o f microorganisms is substantially reduced by their bactericidal and bacteriostatic action, thus achieving full disinfection. Sodium hypochlorite (NaOCl) has been found most efficient in organic compound decomposition and disinfection, and EDTA (a chelating agent) in inorganic compound dissolution. A number o f other, less efficient chemical agents used for the same purpose, is also described. Clinical and experimental studies have shown that none o f the chemical agents currently available is efficient enough to simultaneously remove organic and inorganic components, and provide proper root canal disinfection. Therefore, combinations o f two or more chemical solutions have been used, most efficient of them being a combination o f 10 ml 15% EDTA and 10 ml 2.5% -5.25% NaOCl, provided that alternate washing is performed during and after the root canal instrumentation.