Functional dyspepsia (FD), formerly “nonulcer dyspepsia,” makes up approximately 50 to 75% of dyspepsia presentations. These presentations are defined by having no identifiable structural disease that would explain the symptoms. Recognizing the heterogeneity within the diagnosis of FD, the Rome III criteria further classify FD based on primary symptoms: postprandial distress syndrome and epigastric pain syndrome. The former term refers to bothersome fullness or early satiety with regular meals, whereas the latter is characterized by intermittent epigastric pain or burning that is not predictably meal associated. This review addresses FD, detailing the epidemiology, pathophysiology and pathogenesis, differential diagnosis, diagnosis, treatment, and prognosis. A figure shows the diagnostic algorithm for new-onset dyspepsia. Tables list the Rome III criteria for functional dyspepsia, alarm features in dyspepsia, and medications commonly associated with dyspepsia. This review contains 1 highly rendered figure, 3 tables, and 27 references.