The details of the etiopathogenesis of cystadenolymphoma (Warthin's tumor) are still unclear. To explore the possible risk factors for the development of this tumor, medical records of 81 patients with 96 Warthin's tumors of the parotid glands were compared retrospectively with those of 91 patients with pleomorphic adenoma. The medical history and clinical tumor characteristics of all patients were similar. There were no significant differences between these two patient groups with respect to concomitant diseases, regular medications, and preoperative laboratory findings. However, a significant male predominance of patients with Warthin's tumor could be noted (P<0.05). The male to female ratio was 3.3:1 in patients with Warthin's tumor. Multifocal Warthin's tumor were detected in five cases (6.2%), and 10 patients (12.3%) had bilateral lesions. The odds ratio for the incidence of Warthin's tumor among current smokers compared with never smokers was 8.3 (P<0.0001). Compared with never smokers, clearly higher odds of Warthin's tumor was observed in heavy smokers (more than 30 pack-years) (odds ratio=24.1, P<0.0001) than patients who smoked less than 30 pack-years (odds ratio=4.9, P<0.0001).