The aim of this study was to examine the prevalence of depression and to investigate factors related to depression in a multi-ethnic healthcare practice population. The Primary Care Evaluation of Mental Disorders (PRIME-MD) was used to assess mental disorders in Jordbro Health District, Haninge municipality (JHC), Sweden; 470 adult patients were consecutively examined. A two-stage-screening questionnaire was applied to identify patients reporting five or more of the nine criteria for major depression listed in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV). This procedure was combined with a patient questionnaire (PQ) dealing with questions on socio-demographic characteristics, lifestyle, health status and medicine use. Major depression is common and in this population 18.1% met the criteria for major depression. Also, minor depression was common, with 12.1% of subjects falling into this category. Only 21.2% of the patients with major depression were being treated with anti-depressant medication. Co-morbidity was more common among depressed than among non-depressed patients. Depression seems to be under-recognized in primary care practice. The recognition and treatment of depressive disorders could be improved by using DSM-IV criteria to detect depressive disorders in daily clinical practice in primary care.