['To investigate if HDL cholesterol (HDL-c) could be a biomarker of the degree of severity according to prognostic prediction scores in community-acquired pneumonia (CAP) or the development of clinical complications such as pleural effusion.', 'We included in a retrospective study 107 patients admitted to the hospital that fulfilled diagnostic criteria for CAP between the 30th October 2011 and 1st September 2012. HDL-c levels at admission, CAP prognosis scores (PSI and CURB65) and clinical outcomes were recorded for the study.', 'Basal HDL-c levels were not statistically different according to prognostics scores neither PSI nor CURB-65. Significantly lower levels of HDL-c were also associated to the development of septic shock and admission to the intensive care unit. HDL-c were inversely correlated with acute phase reactants CRP (r\xa0=\xa0-0.585, P\xa0<\xa00.001), ESR (r\xa0=\xa0-0.477, P\xa0<\xa00.001), and leukocytes cell count (r\xa0=\xa0-0.254, P\xa0<\xa00.009). Patients with pleural effusion showed significant lower levels of HDL-c [28.9 (15.5) mg/dl vs. 44.6 (21.1) mg/dl]; P\xa0=\xa00.007. HDL-c is a good predictor of the presence of pleural effusion in multivariate analyses and using ROC analyses [AUC\xa0=\xa00.712 (0.591-0.834), P\xa0=\xa00.006]. HDL-c levels of 10\xa0mg/dl showed a sensitivity of 97.6\xa0% and a specificity of 82.4\xa0% for the presence of pleural effusion.'] Do hDL-c levels predict the presence of pleural effusion and the clinical outcome of community-acquired pneumonia?