Background: Depressive syndromes that do not comply with the diagnostic criteria for specific depressive disorders are designated as ‘subclinical’ or ‘subsyndromal’ depressive syndromes. Using our own data from a clinical study, this paper outlines the significance of subclinical depressive syndromes and demonstrates the problems of differentiating between depressive and subclinical depression (SD) syndromes and organic mood disorders especially in an elderly population with medical comorbidity. Methods: Two hundred and sixty-two patients aged 60 years and older in a general hospital were investigated, using a clinical psychiatric interview, expert ratings and self-report scales after extensive internal medical diagnostic evaluation. Results: When, without further differentiation as to their origin, all symptoms required by symptom checklists according to ICD-10 were considered for the diagnosis of major depression (MD), 35.5% of the study participants fulfilled the diagnostic criteria. After differentiating for etiology of symptoms, MD was found in only 14.1%, SD was diagnosed in 17.6% and organic mood disorder in 12.2% of the study participants. In another 41 patients (15.6%), symptoms of depression not fulfilling ICD-10 criteria were classified as being of organic or drug-induced origin. SD patients were in a mean position between nondepressive and depressive patients with regard to social isolation and physical impairment; women were overrepresented in the depressive and subdepressive groups. Conclusions: SD and organic mood disorder are common and helpful diagnostic categories in the elderly. The results show that in old age there is substantial danger of confounding MD, SD and organic mood disorder, thus leading to erroneously high prevalence rates of MD and underestimations of organic mood disorder if depressive symptoms are recorded only by self-report scales or a symptom checklist. Both internal and psychosomatic-psychotherapeutic competence as well as a liaison service in general hospitals are necessary for the differential diagnosis of MD, SD and organic mood disorder in the elderly with medical comorbidity.