Background: Participant recruitment and retention are long-standing problems in clinical trials. Although there are a large number of factors impacting on recruitment and retention, some of the problems may reflect the fact that trial design and delivery is not sufficiently 'patient-centred' (i.e., sensitive to patient needs and preferences). Most trials collect process and outcome measures, but it is unclear whether patient experience of trial participation itself is routinely measured. We conducted a structured scoping review of studies reporting standardised assessment of patient experience of participation in a trial. Methods: A structured search of Medline, PsycINFO, Embase and CINAHL (Cumulative Index to Nursing and Allied Health Literature) and hand searching of included studies were conducted in 2016. Additional sources included policy documents, relevant websites and experts. We extracted data on trial context (type, date and location) and measure type (number of items and mode of administration), patient experience domains measured, and the results reported. We conducted a narrative synthesis. Results: We identified 22 journal articles reporting on 21 different structured measures of participant experience in trials. None of the studies used a formal definition of patient experience. Overall, patients reported relatively high levels of global satisfaction with the trial process as well as positive outcomes (such as the likelihood of future participation or recommendation of the trial to others). Conclusions: Current published evidence is sparse. Standardised assessment of patient experience of trial participation may provide opportunities for researchers to enhance trial design and delivery. This could complement other methods of enhancing the patient-centredness of trials and might improve recruitment, retention, and long-term patient engagement with trials.