Several studies of representative populations have reported prevalence rates of DSM-III and DSM-III-R generalized anxiety disorder (GAD); however, no community study has examined the effect of the stricter DSM-IV criteria on prevalence estimates and patterns of comorbidity. Furthermore, past studies based on "lifetime" symptom assessments might have led to upper-bound 1-year and point prevalence estimates. Data is presented from a national representative sample study of 4,181 adults in Germany, 18-65 years old, who were interviewed for DSM-IV disorders with the 12-month version of the Munich-Composite International Diagnostic Interview. The prevalence rate of strictly defined, 12-month threshold DSM-IV GAD was estimated to be 1.5%; however, 3.6% of respondents presented with at least subthreshold syndromes of GAD during the past 12 months. Higher rates of worrying and GAD were found in women (worrying 10%, GAD 2.7%) and in older respondents (worrying 9.3%, TAD 2.2%). Taking into account a wider scope of diagnoses than previous studies, a high degree of comorbidity in GAD cases was confirmed: 59.1% of all 12-month GAD cases fulfilled criteria for major depression, and 55.9% fulfilled criteria for any other anxiety disorder. In conclusion, prevalence and comorbidity rates found for DSM-IV GAD are not substantially different from rates reported for DSM-III-R GAD. The minor differences in our findings compared to previous reports are more likely attributable to differences in study methodology rather than changes in diagnostic criteria for DSM-IV.