Recent studies have suggested that exposure to styrene monomer and other solvents is associated with menstrual disturbances. This is the first U.S. study to evaluate the effects of exposure to styrene on dysmenorrhea, intermenstrual bleeding, secondary amenorrhea, menstrual blood clots, and hypermenorrhea. A comprehensive questionnaire was administered to 1,535 blue-collar workers. Multiple logistic regression analyses did not reveal a positive association between styrene exposure and any menstrual abnormality. Risk factors associated with menstrual disturbances included chronic illness with secondary amenorrhea, nulliparity with both decreased blood clots and hypermenorrhea, smoking with blood clots, and age with hypermenorrhea. The overall prevalences of menstrual disorders were 14% for dysmenorrhea, 16% for intermenstrual bleeding, 7% for secondary amenorrhea, 40% for menstrual blood clots, and 31% for hypermenorrhea.