It is known that cigarette smoke induces cytological alterations on the respiratory and olfactory mucosa of the nasal cavity. We evaluated whether cigarette smoking had adverse effects on the epithelium of the vestibule, in the absence of any published ultrasutructural studies. We evaluated ten patients suffering from septum deviation, eight of whom were long-term smokers. While each layer of the epithelium obtained from the non-smokers consisted of a homogeneous cell population, each from the long-term smokers consisted of a heterogeneous cell population. The most prominent changes occurred in the shape and size of the cells and nuclei, the number and length of the cytoplasmic projections, the number and distribution pattern of the desmosomes, and the width of the intercellular spaces. We concluded that cigarette smoke produces hyperplastic and dysplastic changes, important factors related with cancer development, on the epithelium of the vestibule.