The smoking history was surveyed in 128 cases with Warthin tumor of parotid gland in order to investigate the relationship between smoking and the development of the tumor. Two hundred cases of middle or old age normal persons and 136 cases with pleomorphic adenoma in parotid gland served as the controls. The percentage of smoker in patients with Warthin tumor (96.9%) was much higher than that of middle or old age normal persons (25.5%) and patients with pleomorphic adenoma (24.3%). Morever, the amount of smoking was greater and the smoking history was longer in patients with Warthin tumor. When the male and female patients were analysed respectively, the same results were shown. This case--control study suggests that smoking may be one of the etiologic factors associated with the development of Warthin tumor.