['Community acquired pneumonia (CAP) is a major cause of morbidity and mortality. While there is much data about risk factors for severe outcome in the general population, there is less focus on younger group of patients. Therefore, we aimed to detect simple prognostic factors for severe morbidity and mortality in young patients with CAP.', 'Patients of 60 years old or younger, who were diagnosed with CAP (defined as pneumonia identified 48 hours or less from hospitalization) between March 1, 2005 and December 31, 2008 were retrospectively analyzed for risk factors for complicated hospitalization and 90-day mortality.', 'The cohort included 637 patients. 90-day mortality rate was 6.6% and the median length of stay was 5 days. In univariate analysis, male patients and those with co-morbid conditions tended to have complicated disease. In multivariate analysis, variables associated with complicated hospitalization included post chest radiation state, prior neurologic damage, blood urea nitrogen (BUN) > 10.7 mmol/L and red cell distribution width (RDW) > 14.5%; whereas, variables associated with an increased risk of 90-day mortality included age ≥ 51 years, prior neurologic damage, immunosuppression, and the combination of abnormal white blood cells (WBC) and elevated RDW. Complicated hospitalization and mortality rate were significantly higher among patients with increased RDW regardless of the white blood cell count. Elevated RDW was associated with a significant increase in complicated hospitalization and 90-day mortality rates irrespective to hemoglobin levels.'] Does elevated red cell distribution width predict poor outcome in young patients with community acquired pneumonia?