Objectives: The present study was performed to investigate the relationship between work-related factors, including psychological stress, and the formation of a type of oxidative DNA damage, 8-hydroxydeoxyguanosine (8-OH-dG), in order to examine their possible risk factor for occupational carcinogenesis. Methods: A total of 54 healthy workers (27 male and 27 female, aged 41.2 ± 12.5 years) in a company were investigated for 8-OH-dG levels in the peripheral blood leukocytes at the time of a questionnaire survey regarding several factors, such as working hours, workload, fatigue, sleep, psychological stress and the prospect of alleviating it. Subjects were limited to non-smoking and non-drinking workers to exclude the influence of cigarette smoking and alcohol drinking, which have been reported to have associations with the formation of 8-OH-dG. Results: The levels of 8-OH-dG in female subjects were significantly related to the perceived workload (F=5.56, P=0.010), the perceived psychological stress (F=6.15, P=0.007), and the impossibility of alleviating stress (F=3.82, P=0.048). No associations were observed in male subjects. Conclusions: Psychological stress and perceived overwork appear to be related to the pathogenesis of cancer via the formation of 8-OH-dG, particularly in female workers.