Background: The CanRisk tool enables the collection of risk factor information and calculation of estimated future breast cancer risks based on the multifactorial Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) model. Despite BOADICEA being recommended in NICE guidelines and CanRisk being freely available for use, the CanRisk tool has not yet been implemented widely in primary care. Aim: The aim of this study was to explore the barriers and facilitators to the implementation of the CanRisk tool in primary care. Design and setting: A multi-methods study, conducted with primary care practitioners (PCPs) in the UK. Methods: Three methods were employed. Participants completed two vignette-based case studies, a semi-structured interview and a questionnaire. Results: 16 PCPs completed the study. The main barriers to implementation were: the time needed to complete the tool, competing priorities, IT infrastructure, and PCPs’ lack of confidence and knowledge to use the tool. The main facilitators included: easy navigation of the tool, its potential clinical impact, and the increasing availability of and expectation to use risk prediction tools. Conclusion: This more developed understanding of the barriers and facilitators to the use of CanRisk in primary care highlights that future implementation activities should focus on reducing the time needed to complete a CanRisk calculation, integrating the CanRisk tool into existing IT infrastructure, and identifying appropriate contexts in which to conduct a CanRisk calculation. PCPs may also benefit from information about cancer risk assessment and CanRisk specific training.