Proton pump inhibitor therapy (PPI) has been used for over a decade to successfully treat patients with gastro-oesophageal reflux disease (GORD); however it has been shown that 35-40% of patients with GORD have persistent symptoms on therapy. Combined multichannel intraluminal impedance-pH (MIIpH) is a clinically available tool that has the ability to detect reflux episodes independent of the pH. MIl-pH identifies the refluxate by impedance changes produced by the bolus presence in the oesophagus and classifies it into acid or non-acid by concomitant changes in intraluminal pH. The 2.1 mm MIl-pH cathteter is positioned Scm above the manometrically located proximal border of the lower oesophageal sphincter (LOS) and allows monitoring changes in . intraluminal impedance at 3, 5, 7, 9, 15 and 17cm above the LOS. In our institution we have showed that approximately half of the patients with typical symptoms and almost one-quarter with atypical symptoms despite PPI b.d are associated with reflux (non-acid or acid). This means that the majority of patients with persisting atypical symptoms despite PPI b.d have no reflux associated with their symptoms and an alternative cause should be sought. Medical therapy is potentially available in the form of baclofen, a y-aminobutyric acid Bagonist which inhibits transient lower oesophageal relaxations, but unfortunately its therapeutic use is limited by its side-effects. Laparascopic Nissen fundoplication (LNF) has been used to treat patients' refractory to PPI therapy with a positive symptom index with reflux after MIl-pH testing. Eighteen patients with symptoms identified as associated with reflux during MIl-pH testing referred for to surgery for LNF. In conclusion MIl-pH testing should be used to clarify the diagnosis of patients who continue to have persistent symptoms on maximal acid suppression therapy. Those patients with proven symptom association with impedance-documented ongoing reflux may benefit from antireflux surgery.