PURPOSE: To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the sophagogastric junction of young male rats Wistar, simulating injury caused by astroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. METHODS: Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, astroesophageal reflux and control group. RESULTS: The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim) and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. CONCLUSION: The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.27115de Stefani, E., Correa, P., Oreggia, F., Leiva, J., Rivero, S., Fernandez, G., Deneo-Pellegrini, H., Fontham, E., Risk factors for laryngeal cancer Cancer, 60 (12), pp. 3087-3091. , 198715Koufman, J.A., Burke, A.J., The etiology and pathogenesis of laryngeal carcinoma (1997) Otolaryngol Clin North Am, 30 (1), pp. 1-19del Negro, A., Araújo, M.R., Tincani, A.J., Meirelles, L., Martins, A.S., Andreollo, N.A., Experimental carcinogenesis on the oropharyngeal mucosa of rats with hydrochloric acid, sodium nitrate and pepsin (2008) Acta Cir Bras, 23 (4), pp. 337-342Copper, M.P., Smit, C.F., Stanojcic, L.D., Devriese, P.P., Schouwenburg, P.F., Mathus-Vliegen, L.M.H., High incidence of laryngo-pharyngeal refux in patients with head and neck cancer (2000) Laryngoscope, 110, pp. 1007-1011Wight, R., Paleri, V., Arullendran, P., Current theories for the development of nonsmoking and nondrinking laryngeal carcinoma (2003) Curr Opin Otolaryngol Head Neck Surg, 11 (2), pp. 73-77Galli, J., Cammarota, G., Calo, L., Agostino, S., D'ugo, D., Cianci, R., Almadori, G., The role of acid and alkaline refux in laryngeal squamous cell carcinoma (2002) Laryngoscope, 112 (10), pp. 1861-1865Bacciu, A., Mercante, G., Ingegnoli, A., Bacciu, S., Ferri, T., Refux esophagitis as a possible risk factor in the development of pharyngolaryngeal squamous cell carcinoma (2003) Tumori, 89 (5), pp. 485-487Ozlugedik, S., Yorulmaz, I., Gokcan, K., Is laryngopharyngeal refux an important risk factor in the development of laryngeal carcinoma? (2006) Eur Arch Otorhiolaryngol, 263 (4), pp. 339-343El-Serag, H.B., Hepworth, E.J., Lee, P., Sonnenberg, A., Gastroesophageal refux disease is a risk factor for laryngeal and pharyngeal cancer (2001) Am J Gastroenterol, 96 (7), pp. 2013-2018Wright, J.L., Churg, A., Cigarette smoke causes physiologic and morphologic changes of emphysema in the guinea pig (1990) Am Rev Respir Dis, 142 (6), pp. 1422-1428Biselli, P.J.C., (2008) Effect of Exposure to Cigarette Smoke and Diesel Oil Residue In the Lungs of Mice C57/B16 9 (Doctoral Thesis), , University of Sao Paulo: Faculty of MedicineQuinn, R., Comparing rat's to human's age: How old is my rat in people years? (2005) Nutrition, 21, p. 777D'agostini, F., Balansky, R.M., Izzotti, A., Lubet, R.A., Kelloff, G.J., de Flora, S., Modulation of apoptosis by cigarette smoke and cancer chemopreventive agents in the respiratory tract of rats (2001) Carcinogenesis, 22 (3), pp. 375-380Shapiro, S.D., Animal models for COPD (2000) Chest, 117, pp. 223S-227SAndreollo, N.A., Lopes, L.R., Coelho-Neto, J.S., Gastroesophageal refux disease: What is the effectiveness of diagnostic tests? (2010) ABCD Arq Bras Cir Dig, 23 (1), pp. 6-10Koufman, J.A., Laryngopharyngeal reflux is different from classic gastroesophageal reflux disease (2002) Ear Nose Throat J, 81 (9 SUPPL 2), pp. 7-9Bulmer, D.M., Ali, M.S., Brownlee, I.A., Dettmar, D.W., Pearson, J.P., Laryngeal mucosa: Its susceptibility to acid and pepsin (2010) Laryngoscope, 120 (4), pp. 777-782Francis, D.O., Maynard, C., Weymuller, E.A., Reiber, G., Merati, A.L., Yueh, B., Reevaluation of gastroesophageal refux disease as a risk factor for laryngeal (2011) Cancer, 121, pp. 102-105Nurgalieva, Z.Z., Graham, D.Y., Dahlstrom, K.R., Wei, Q., Sturgis, E.M., A pilot study of Helicobacter pylori infection and risk of laryngopharyngeal cancer (2005) Head Neck, 27 (1), pp. 22-27Winter, J.W., Paterson, S., Scobie, G., Preston, T., McColl, K.E., N-nitrosamine generation from ingested nitrate via nitric oxide in subjects with and without gastroesophageal refux (2007) Gastroenterology, 133 (1), pp. 164-174Modena, S.F., Meirelles, L.R., Araújo, M.R., Lopes, L.R., Andreollo, N.A., Role of nitrites in the genesis of adenocarcinoma associated with Barrett's esophagus (2009) In Vivo, 23 (6), pp. 919-923Cherry, J., Margulies, S.I., Contact ulcer of the larynx (1968) Laryngoscope, 78 (11), pp. 1937-1940Adams, J., Heintz, P., Gross, N., Andersen, P., Everts, E., Wax, M., Cohen, J., Acid/pepsin promotion of carcinogenesis in the hamster cheek pouch (2000) Arch Otolaryngol Head Neck Surg, 126, pp. 405-409Goldberg, H.I., Dodds, W.J., Gee, S., Montgomery, C., Zboralske, F.F., Role of acid and pepsin in acute experimental esophagitis (1969) Gastroenterology, 56 (2), pp. 223-230Lillemoe, K.D., Johnson, L.F., Harmon, J.W., Role of components of the gastroduodenal contents in experimental acid esophagitis (1982) Surgery, 92 (2), pp. 276-284