Background: This study examines the presence of obsessions in the general population and in various psychiatric disorders. Second, the impact of obsessions is studied in terms of general functioning and quality of life in the general population. Methods: Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a large representative sample of the Dutch population (n = 7,076). Diagnostic criteria were assessed by the Composite International Diagnostic Interview (CIDI). The association of quality of life and obsessions on each subject was assessed by using Short Form 36 Health Survey (SF-36) and General Health Questionnaire (GHQ). Results: Obsessions occurred frequently in the general population: the lifetime prevalence of obsessions was 5.3% and the 12-month prevalence was 1.7%. Subjects with obsessions scored significantly worse (P<.0001) on all eight dimensions of the SF-36 as well as on the GHQ. When controlling for the presence of any mental disorder, the negative association of obsessions and low general health and well-being remained significantly intact. In patients with a psychiatric disorder, obsessions had a lifetime prevalence of 10.3% and a 12-month prevalence of 6.8%. Conclusions: Obsessions are common phenomena in the general population and are associated with decreased functioning in several areas of health and well-being. Furthermore, they occur frequently in the presence of various psychiatric disorders. Obsessions should be perceived, similar to delusions, as a distinct dimension across psychiatric disorders rather than a mere symptom of OCD. Depression and Anxiety, 2011. © 2011 Wiley-Liss, Inc.