Background: This paper provides nationally representative data on how current and past mental disorders are related to functional disability and health-related quality of life (QoL). Methods: Results are based on a nationally representative sample (DEGS1-MH; n=4483 aged 18-79). Respondents were examined by clinical interviewers with the DSM-IV Composite International Diagnostic Interview (DIA-X/M-CIDI). Functional disability, i.e. number of disability days in the past 4 weeks, and QoL, i.e. mental (MCS) and physical (PCS) component scale of the SF-36V2, were examined in subjects with 12-month mental disorders (= active cases [AC]) and compared to (a) subjects who never met diagnostic criteria (= unaffected individuals [UAI]), and (b) those with a history of mental disorders but not meeting the diagnostic criteria in the past 12 months (= non-active cases [NAC]; partially or fully remitted). Results: In comparison to UAI (mean: 1.9), AC reveals a 2-3 fold disability days/month (5.4, P< .001) and a substantially reduced MCS (UAI: 52.1; AC: 43.3, P< .001). NAC had a similar number of disability days as UAI, but significantly reduced MCS scores (49.9; P< .001). Disability days and QoL decrements were highest in internalizing disorders including somatoform disorders and most pronounced in comorbid cases. Conclusions: By and large, findings of a previous study were confirmed and extended for this nationally representative German sample. 12-month mental disorders, particularly internalizing, including somatoform disorders, are associated with high levels of disability and increased health-related QoL decrements. Partial or complete remission of the mental disorders is associated with a normalization of the numbers of disability days.