Women with bipolar disorder commonly report premenstrual exacerbation. Similar to the prevalence rate in the report by Dias et al., estimates are generally in the range of 60%—70% (2, 3) with retrospective reporting. There have been a number of case reports of women with bipolar disorder who regularly experience hypomanic or manic symptoms premenstrually. Despite the high prevalence of self-reported premenstrual exacerbation, several prospective studies have not demonstrated consistent mood changes associated with menstrual cycle phase in the general population of women with bipolar disorder. For example, Shivakumar et al. (4) examined the charts of 41 women with bipolar disorder (including types I, II, not otherwise specified, and schizoaffective) who prospectively completed NIMH Life Chart Method daily ratings of mood over 3 consecutive months, and the authors did not find any association between changes in depression or mania with phases of the menstrual cycle. This echoed earlier work by Leibenluft et al. (5), who followed 25 women with rapid-cycling bipolar disorder with daily mood ratings for 3 months or longer and found no association between mood and menstrual cycle. Although the numbers of subjects were small, these studies indicate that there is no direct and consistent link between mood and menstrual cycle in the general population of women with bipolar disorder. However, these studies do not rule out the possibility that there is a subgroup of women with bipolar disorder who are sensitive to times of hormonal change and who experience premenstrual exacerbation.