-This study was aimed at understanding the relationship among menstrual pattern, dysmenorrhea, life style and working conditions in nurses. The nurses were randomly selected from a medical center in Northern Taiwan. Each subject completed daily records including life and working conditions during the study period. The study showed that there were statistically significant differences in work years, daily working hours and type of work shift among nurses that worked at different units in the hospital. In the perceived regular cycle group, nurses that worked the night shift only exhibited the shortest menstrual cycles, less than 25 d. There was a significant difference (p<0.05) among the nurses' menstrual cycles. Many life factors (such as passive tobacco smoke exposure, perceived life satisfaction and perceived life stress) and working factors (such as work years, perceived work satisfaction and perceived work stress) were not significantly related to menstrual cycle regularity. In addition, 30% of the nurses complained of dysmenorrhea. Some factors including age, marital status and perceived life satisfaction were significantly related to dysmenorrhea. However, other life factors (such as passive tobacco smoke exposure, smoking, coffee, alcohol, cold drink habits, exercise and perceived life stress) and working factors (such as working places, type of work shift, daily work hours, perceived work satisfaction and perceived work stress) showed no correlation with dysmenorrhea. This study indicates that women should pay attention to their menstrual function and dysmenorrhea phenomenon. (J Occup Health 2005; 47: 149-156)