Background: Little is known about the characteristics and real world life circumstances of ARDS (acute respiratory distress syndrome) patient populations. This knowledge is essential for transferring evidence-based therapy into routine healthcare. The aim of this study was to report socio-demographic and clinical characteristics in an unselected population of ARDS patients and to compare these results to findings from other large ARDS cohorts. Methods: A German based cross-sectional observational study was carried out. A total of 700 ARDS patients were recruited in 59 study sites between September 2014 and January 2016. Socio-demographic, disease and care related variables were recorded. Additionally, characteristics of other large ARDS cohorts identified by a systematic literature search were extracted into evidence tables. Results: Median age of ARDS patients was 58 years, 69% were male. Sixty percent had no employment, predominantly due to retirement. Seventy-one percent lived with a partner. The main cause of ARDS was a pulmonary 'direct' origin (79%). The distribution of severity was as follows: mild (14%), moderate (48%), severe (38%). Overall ICU mortality was calculated to be 34%. The observed prevalence of critical events (hypoxemia, hypoglycemia, re-intubation) was 47%. Supportive measures during ICU-treatment were applied to 60% of the patients. Other ARDS cohorts revealed a high heterogeneity in reported concomitant diseases, but sepsis and pneumonia were most frequently reported. Mean age ranged from 54 to 71 years and most patients were male. Other socio-demographic factors have been almost neglected. Conclusions: The proportion of patients suffering of mild ARDS was lower compared to the only study identified, which also applied the Berlin definition. The frequency of critical events during ICU treatment was high and the implementation of evidence-based therapy (prone positioning, neuro-muscular blockers) was limited. More evidence on socio-demographic characteristics and further studies applying the current diagnostic criteria are desirable.