There is a growing perception that biomedical research has focused more on the health problems of men relative to those of women and that women have been denied access to advances in medical diagnosis and therapy as a result of being excluded from clinical studies. Women and Health Research, Volume 2, addresses issues connected with women's participation in clinical studies: ethical issues related to recruitment, retention, and the inclusion of pregnant women and other women of childbearing age; legal issues such as liability, compensation for injury, constitutional concerns, and federal regulations; and health consequences associated with exclusion or underrepresentation. The commissioned papers focus on the research participation of women from specific racial and ethnic groups and on whether women have been underrepresented in biomedical research, based on a systematic survey of clinical studies reported in a prominent medical journal.