Background: Patients may be unwilling to participate in clinical trials if they perceive risks. Outcomes were evaluated following surgery for gastro-oesophageal reflux in patients recruited to randomized trials compared with patients not in trials. Methods: This study compared outcomes of patients who had surgery for reflux within or outside randomized trials between 1994 and 2009. The choice of procedure outside each trial was according to surgeon or patient preference. Clinical outcomes were determined 1 and 5 years after surgery using a standardized questionnaire, with analogue scales to assess heartburn, dysphagia and overall satisfaction. Subgroup analysis was undertaken for those aged less than 75 years undergoing laparoscopic Nissen fundoplication. Results: Some 417 patients entered six randomized trials evaluating surgery for reflux and 981 underwent surgery outside the trials. The trial group contained a higher proportion of men and younger patients, and patients in trials were more likely to have undergone Nissen fundoplication. At 1 year, patients in the trials had slightly lower heartburn scores and less abdominal bloating, but otherwise similar outcomes to those not in the trials. At 5 years there were no differences, except for a slightly higher dysphagia score for liquids in the trial group. For the subgroup analysis, demographic data were similar for both groups. There were no differences at 1 year, but at 5 years patients enrolled in the trials had higher scores for dysphagia for liquids and heartburn. All of the statistically significant differences were thought unlikely to be clinically relevant. Conclusion: Participation in a randomized trial assessing surgery for reflux did not influence outcomes.