In 2001 FDA (Food and Drug administration, USA) gave its permission for simultaneous oesophageal intraluminal impedance examination and pH testing in the clinical practice. In 2002 in Porto, Portugal, a committee of international experts proposed a new classification of reflux types.Material and methods. From October 2005 to June 2006, we examined 36 patients sent to the clinic with GERD symptoms using a Sleuth® recording device.Results. The group of 36 patients (19 women and 17 men); mean age of 47 years with a range of 16-74 years) was examined. The mean length of time for the examination was 22 h 47 min, the shortest one lasting 18 h 36 min; brakes were caused by battery failure. 1509 episodes of reflux were confirmed by impedance channels. Only 538 (35.65%) of these reflux episodes were acidic or weakly acidic and 971 (64.35%) were non-acidic. There was one patient without acid reflux episodes during examination and only 12 non-acidic episodes. The proximal extend, defined as 15 cm above the LES, achieved 616 reflux episodes (40.82%). None of the patients had abnormal physical clearing times; 5 had extended chemical clearing times (13.8%) in recumbent positions.Summary. This paper is not a statistical evaluation of a MII-pH study and is only a report of our first experiences with this new diagnostic method. Objective evaluation of symptom correlation to reflux in MII and the chemical character of the refluxate gives a much more precise qualification to the best type of treatment. In cases of non-acidic reflux, MII-pH testing hastens decision making about surgery.