As American society has become increasingly medicalized, biomedically shaped constructions of risk have begun to dominate traditional cultural constructions. This paper examines how the quest for a pregnancy affects the construction of risk by women in infertility treatment in the United States. Findings are based on a longitudinal, qualitative study with 275 persons (132 couples and 11 women) who experienced infertility. Because women's involvement in medical treatment was greater than that of men and because they were more intent on treatment, women assumed the role of final arbiter of what was a risk, and which risks to take. Women perceived more risks than men and were more willing to take risks than men. Notions of risk changed for both women and men, however, as they proceeded through medical treatment. This research suggests that once infertility is medically designated as a disease, both patients and practitioners pursue a 'cure' through a well-delineated pattern of medical treatment, despite the risks of such treatment and independent of the likelihood of success. When medical views of risk and responsibility are teamed with women's persistence in the pursuit of a pregnancy, medical treatment may be taken to extremes. Americans consider risk-taking to be their prerogative when personal histories reflect strong cultural mandates about norms, values, rights, and responsibilities, and these in turn are interpreted as health-related by both consumers and health professionals. As a consequence, the forces that trigger medicalization are activated and medical technology is given potentially limitless scope.