"Idiopathic gastroparesis" is a poor term to describe this very heterogeneous syndrome. Pathophysiology may not be "idiopathic," but merely unidentifiable with conventional methods suggested for gastroparesis. The diagnosis of "gastroparesis" suggests that delayed gastric emptying is the underlying cause of symptoms, but this description fails to explain the variable presentation. There are fundamental differences in pathophysiology, clinical presentation, severity, and future prognosis among patients with idiopathic gastroparesis. Understanding these differences is necessary in order to provide cost-effective treatment in these patients.