Functional heartburn (FH) is a functional gastro-intestinal disorder characterized by symptoms of heartburn not related to gastro-esophageal reflux. The absence of evidence of reflux-related symptoms relies on absence of esophagitis at endoscopy (including biopsies to exclude eosinophilic esophagitis), a normal esophageal acid exposure during esophageal pH-monitoring together with a negative symptom-reflux association analysis and an unsatisfactory response to proton pump inhibitor therapy. Addition of impedance measurement to pH-monitoring is likely to increase the number of patients with recognized reflux-related symptoms. The pathophysiology of functional heartburn remains largely unknown but involves disturbed esophageal perception and psychological factors such as depression, anxiety and somatization. The treatment of FH remains largely empirical and an individual approach is therefore recommended. The clinician should provide reassurance and refrain from performing too many invasive tests or therapeutic procedures. The use of pain modulators is recommended by most experts despite the lack of appropriate clinical trials to support it.