Risk for colorectal cancer, breast cancer, heart disease and diabetes has both a familial and a lifestyle component. This quasi-experimental study aimed to determine whether a Family Health History (FHH) assessment and the subsequent provision of risk information would increase young adults' (17-29 years) intentions to modify health behaviours associated with the risk of these chronic diseases (i.e. alcohol consumption, fruit and vegetable intake and physical activity) and to talk to their family about their risk.After baseline measures of current and intended health-related behaviours, participants (n = 116) were randomly allocated to either a FHH assessment or control information. Based on the FHH provided, participants in the FHH condition were then classified as 'above-average risk' or 'average risk'. One week later, participants were provided with tailored health information and completed follow-up measures of intended health-related behaviours and perceived vulnerability.Participants classified as 'above-average risk' had increased perceptions of vulnerability to a chronic disease. Despite this, no group differences were found in intentions to change physical activity or fruit and vegetable consumption. Participants with above-average risk reported greater intentions to decrease the frequency of their alcohol consumption than average risk/control participants. In addition, completing a FHH assessment promoted intended communication with family members about chronic disease risk.FHH assessments may have the greatest value within the family context. SO WHAT? Future research could examine the impact of providing FHH information to different family members as a health promotion strategy.