The objective of this study was to evaluate the histopathologic and immunohistochemical effects of propineb on rat nasal mucosa. Twenty adult Sprague-Dawley rats weighing 180-220 g, were used as experimental animals. The rats were divided into propineb and control groups. The control group received distilled water with spray at the same time period. The experiment was terminated after three weeks. In each case, sections of the nosewere taken. In experimental group, microscopic examination of nasal respiratory mucosa revealed that degenerative changes in epithelium were observed in sections of propineb-treated group. There were also leukocyte infiltration and vascular dilatation detected in the connective tissue. We detected CD34-immunoreactive mononuclear cells and endothel cells in the lamina propria of propineb group. In propineb group compared to the control group, the respiratory epithelium, goblet and basal cell nuclei were stained positive for PCNA. Propineb inhalation may be irritating to the nasal mucosa.