Patient-reported benefits of research participation have been described by study participants; however, many studies have small sample sizes or are limited to patient groups with poor prognoses. The purpose of this study was to explore the effects of research participation on patient experience using survey responses from a large, national sample of cancer patients (N = 66 462) and interviews with breast cancer patients attending a London trust. Multivariate logistic regression was used to investigate associations between taking part in research and positive patient experience. Based on our analysis, patients who participated in research were more likely to rate their overall care and treatment as 'very good/excellent' (ORadj :1.64, 95%CI: 1.53-1.76, P < 0.001) and to describe positive patient experiences, such as better access to non-standard care, better interactions with staff and being treated as an individual. However, findings from our interviews indicated that there was no common understanding of what constitutes cancer research and no clear delineation between research participation and standard care, from the patient perspective. Further work to explore how participation positively influences patient experience would be useful to develop strategies to improve care and treatment for all patients regardless of whether or not they choose, or have the opportunity, to take part in research.