Uncertainty is central to the experience of genetic decision making and counseling about cancer risk. Women seeking genetic counseling about their breast cancer risk may experience a great deal of uncertainty about issues related to their daughters. We used a theory of Communication and Uncertainty Management to guide analysis of sources of uncertainty about daughters that emerged during 16 video-recorded and transcribed conversations between mothers at risk for a BRCA 1/2 mutation and their genetic healthcare practitioners. An interpretive design and constant comparative method revealed three dominant patterns or themes representing sources of uncertainty mothers have relating to their daughters: disease risk, future cancer screening, and communication of related information to daughters. Both practitioners and mothers discussed these aspects of uncertainty. The findings identify the significant role uncertainty and familial concerns play in mothers' genetic testing decision making process. To assist genetic practitioners, we highlight daughter-related concerns that mothers are uncertain about and which are vital to their genetic counseling needs.