['We aimed to explore the association between vitamin D levels and the severity, mortality and microbiological etiology of community-acquired pneumonia.', 'Vitamin D levels (both, the reservoir form 25-OH and the activated form 1,25-OH2) of 300 randomly selected patients with community-acquired pneumonia due to pre-specified pathogens included in the German competence network (CAPNETZ) study were measured. Prior to statistical analysis, values of 25-OH and 1,25-OH2 were power-transformed to achieve parametric distribution. All further analyses were performed with seasonally and age adjusted values.', 'There was only a modest (Spearman Coefficient 0.38) positive correlation between 25-OH and 1,25-OH2. For 1,25-OH2 but not 25-OH, the general linear model revealed a significant inverse correlation between serum concentration and CURB score (p\u2009=\u20090.011). Liver and respiratory co-morbidity were associated with significantly lower 25-OH values and renal co-morbidity with significantly lower 1,25-OH2 values. No significant differences of 1,25-OH2 or 25-OH between different pathogens (influenza virus, Legionella spp., Streptococcus pneumoniae) were detected.'] Are vitamin D deficiency in community-acquired pneumonia : low levels of 1,25 ( OH ) 2 D associated with disease severity?