Women with a personal or maternal history of breast cancer experience psychological stress in relation to breast cancer risk, and adolescent and young adult daughters are particularly at risk for experiencing stress related to their mothers' history of breast cancer. The current study examined interpersonal and biological stress responses during a laboratory-based communication task about breast cancer risk in 32 mother-daughter dyads and explores whether certain communication styles between mothers and daughters are associated with increased stress reactivity during the task. Five saliva samples were collected from each participant to determine cortisol baseline levels, reactivity to, and recovery from the task. Negative maternal communication was associated with higher cortisol levels in daughters. In addition, maternal sadness was correlated with lower levels of daughters' cortisol at all time points with the exception of baseline measures. Implications for understanding the psychobiology of stress in women at risk for breast cancer are highlighted.