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 causes, symptoms, and prognosis among patients with idiopathic gastroparesis. Understanding these differences is necessary in order to provide effective treatment in these patients. We believe our classification for gastroparesis is a useful tool in the management of patients with idiopathic gastroparesis to predict clinical severity, treatment response, and future prognosis.