To compare the effectiveness of medical (antacids, histamine antagonists and proton pump inhibitors) and surgical (fundoplication) treatment of chronic GORD. Patients with objective (endoscopic or pH) evidence of chronic reflux reported in 6 randomised trials and 3 cohort studies, 1966-1999. Systematic review of comparative studies identified from electronic searches, citations, manual searches of journals, and correspondence with authors and experts. Improvements in prevalence or severity of symptoms, oesophagitis, pH reflux duration, lower oesophageal sphincter pressure, patients' satisfaction, and side-effects. Improved outcomes were more common after surgical than medical treatment with significant differences in objective outcomes in 5/6 randomised trials and in 2/3 cohort studies. Subjective outcomes (symptoms and patients' satisfaction) were also more common among surgical patients in all but one study that assessed them. Odds ratios for improvement with surgical rather than medical treatment ranged from 1.2 to 200, and numbers needed to treat ranged from 1.2 to 58, where these could be calculated. Studies were too heterogeneous for meta-analysis. In trials of chronic severe GORD, surgery is consistently more effective than medical treatment in relieving symptoms and objective oesophagitis, although omeprazole can give similar symptom relief with adjustment of the dose.