Lower esophageal sphincter pressure has been assessed pre-operatively, intra-operatively,and more than 6 months postoperatively in 34 patients having antireflux surgery for gastro-esophageal reflux disease. The sphincter pressures associated with the outcome in relation to pH measured reflux and the symptoms of recurrent heartburn, gas bloating, and dysphagia have been determined. There was no significant difference between the intra-operative sphincter pressure or the postoperative sphincter pressure and any of these parameters. It is concluded that intra-operative manometry in its present form is not useful in antireflux surgery for primary gastro-esophageal reflux disease.