The diagnosis of generalized anxiety disorder (GAD) was first introduced in 1980 with the publication of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-III) of the American Psychiatric Association. Prior to this, the diagnosis of "anxiety neurosis" was given to patients with symptoms similar to those now incorporated within the GAD category. Originally, GAD was created as a residual category within the anxiety disorders as a rubric for patients with serious anxiety problems but without panic attacks. Panic disorder therefore received far more research attention, and GAD was seen as a diagnosis of exclusion once panic disorder had been ruled out. It is now clear, however, that GAD is a serious psychiatric disorder that is more common than panic disorder and frequently encountered in primary care practice. Indeed, the primary care physician is more likely to see patients with pure GAD than is the psychiatrist. While the treatment of GAD is relatively straightforward, the diagnosis can be difficult. Hence, careful attention to several key symptomatic presentations is important.