ObjectivesPatients’ first-hand experiences of faecal microbiota transplantation (FMT) performed in a rheumatological care setting have yet to be elucidated. The objectives were to explore participants’ perceptions of being part of an FMT trial thereby identifying potential trial participation effects and enlightening the patient perspective on the outlook for future FMT trials in rheumatic diseases.DesignIn a qualitative study nested within a double-blind, randomised, placebo-controlled trial (RCT) testing FMT as a potential new antirheumatic treatment, semistructured telephone interviews were conducted following the trial participants’ final 26-week visit. Qualitative researchers, who did not take part in the main trial, performed the interviews and the primary analysis. The experiences explored related to the conduct of the RCT and changes in the participants’ everyday life. The analysis was carried out using a thematic approach.SettingA Danish rheumatology university outpatient clinic with nationwide inclusion.ParticipantsThe study included 10 patients with psoriatic arthritis (PsA) who were unaware of their treatment allocation (FMT/sham transplantation) and completed the final 26-week trial visit.ResultsParticipation in the RCT influenced the patients’ understanding of PsA and induced positive changes in their everyday life. Renewed hopes for the future in addition to a feeling of enhanced care contributed to significant trial participation effects. FMT was deemed a tolerable and safe treatment.ConclusionsDiscrepancies between the clinical and the research setting should be considered when discussing the clinical relevance of the results of the RCT. Overall, patients with PsA who have participated in an RCT testing FMT find the treatment acceptable and safe encouraging more research into the field of microbiota-targeted interventions in rheumatic diseases.Trial registration numberNCT03058900; Pre-results.