Objective: Options for revising the DSM-IV Generalized Anxiety Disorder (GAD) diagnostic criteria have been made by the DSM-5 Anxiety, Obsessive-Compulsive, Post-traumatic and Dissociative Disorders Work Group. It has been proposed that renaming the disorder Generalized Worry Disorder, clarifying criterion A to emphasize the primacy of worry, reducing the duration required, altering the list of associated symptoms to reflect the concomitants of worry that are specific to GAD, and adding behavioural criteria could clarify the concept of chronic worry for clinicians and enhance the reliability of the diagnosis. The influence of the proposed changes on the prevalence and severity of cases is examined. Method: Data from a national survey and from a clinical data set were used to quantify the effect of the proposed changes. Results: Reducing the duration from 6 to 3 months and removing the clinical significance criterion raised the prevalence of GAD, whereas revising the associated symptoms and adding behavioural symptoms reduced the prevalence. With all the new options implemented, although the prevalence of the diagnosis rose by 9%, it was associated with similar levels of distress and impairment as DSM-IV cases. Conclusions: There is preliminary evidence that the proposals may increase the prevalence of GAD but may not influence the severity of cases. The clinical utility, reliability and validity of the diagnosis remains to be established.