BACKGROUND Due to the high prevalence and incidence of patients with gastroesophageal reflux disease (GERD), the diagnostic workup of patients with symptoms of GERD needs to be balanced between empiric antisecretory therapy and further functional assessment including endoscopy and reflux monitoring. METHODS This article is based on a literature review (PubMed, Medline) using the terms 'gastroesophageal reflux disease' or 'GERD' and 'diagnosis', 'therapy', or 'PPI' with special and critical analysis of the current 'Porto' consensus report. CONCLUSIONS Further diagnostics are mandatory in case of alarm symptoms as well as atypical or persistent symptoms under adequate therapy with proton pump inhibitors (PPI). In general, the clinical situation needs to be clarified before sending the patients for reflux monitoring. The question is not only when and whom to test but also how to test: on or off PPI therapy, pH-metry, or combined pH-impedance analysis. These questions have been defined in a recent consensus report of an international panel of experts and are further discussed in this article.