<qa>  What was the aim of the study?The aim of the study was to evaluate the applicability of the Physical Activity Scale PAS in relation to patients with severe mental illness. The study hypothesised that physical activity levels among patients with severe mental illness was significantly lower than healthy controls. The physical activity level of patients with severe mental illness attending Aarhus University Hospital, Risskov in comparisons with healthy controls matched on gender and age was assessed with PAS. 