Objective: Experimentally to show the histopathologic alterations in the trachea and lungs due to long term exposure to biomass smoke in rats. Material and Methods: 30 female Wistar-Albino adult rats were used in the experiment. The rats were exposed to biomass smoke for one hour a day for 3, 6, and 9 months. At the end of the experiment, the rats were decapitated under deep anesthesia. The tissue samples were taken and were processed for histopathological examinations. Results: Gross findings were focal small anthracotic accumulations, multiple abscesses, cysts with mucinous fluid and emphysematic changes in the lungs. Histopathologically, lymphocytic, eosinophilic and macrophage infiltrations in varying densities were observed in the interstitium of the lungs. Based on the exposure time, small papillary structures were observed in the airway mucosa. As most apparent in pulmonary veins, the intimae and media of the pulmonary vessels were thickened and their lumens were narrowed. In one case, we noticed papillary adenomatous proliferation of the mucosa. In tracheal mucosa, the anthracotic spots were encountered. We also observed ulceration, erosion areas and squamouse metaplasia in the tracheal mucosae. Conclusion: Long-term exposure of rats to biomass smoke was associated with chronic inflammatory and premalignant alterations in different regions of the respiratory trac such as trachea, bronchia, bronchioles, and parenchyma including subpleural areas.