OBJECTIVES:  Major Depressive Disorder (MDD) has a profound negative impact on sufferers’ lives.  This analysis sought to identify differences in patient characteristics and outcomes associated with self-report of depression and use of prescription treatment within a positively-screened MDD population. METHODS:  Data were taken from the US 2011 National Health and Wellness Survey (n=75,000), a cross-sectional Internet-based survey representative of US adults.  Patients with MDD were identified using the Patient Health Questionnaire (PHQ-9).  Health-related quality of life (HRQoL) was assessed with the SF-12 Health Survey (SF-12v2), and activity impairment was measured with the Work Productivity and Activity Impairment questionnaire (WPAI).   Comparisons between patient groups were made with chi-square tests for categorical variables and ANOVA for continuous variables. RESULTS:   PHQ-9 scores identified MDD in 6.3% of respondents (n=4,720); 33.5% (n=1,583) reported depression and prescription treatment, 30.0% (n=1418) reported depression without prescription treatment, and 36.4% (n=1719) did not self-report depression. Compared to those who did not self-report depression, treated patients were more likely to have severe depression according to PHQ-9 scores (32.5% vs. 22.2%), had lower mental HRQoL (28.5 vs. 37.3), and more activity impairment (60.5% vs. 47.4%) (ps<0.001); however, fewer treated patients visited the emergency room in the past 6 months (25.0% vs. 21.3%, p<0.001).  Patients who did not report depression were more likely to have completed college (34.6% vs. 30.6%) and had higher incomes (37.6% with incomes over $50,000 vs. 32.4%), but were less likely to have insurance (70.5% vs. 80.6%), and those with insurance were less likely to have prescription drug coverage (60.2% vs. 74.4%) (ps<0.001). CONCLUSIONS: Patients who had MDD according to PHQ-9 but did not report depression had less severe depression and a higher mental QoL than treated patients, but still had poor health outcomes.  Less comprehensive insurance coverage may be a barrier in seeking treatment.