Aims: Metabolic Syndrome has become the greatest health hazard in the modern world, along with infectious diseases. We aimed to evaluate the effects of metabolic syndrome on disease course, laboratory values and mortality in patients with COVID 19 pneumonia. Methods: COVID 19 pneumonia patients with and without metabolic syndrome were compared in terms of laboratory parameters, clinical results and mortality rates retrospectively. Results: A total of 194 patients hospitalized with COVID 19 pneumonia (with and without metabolic syndrome n = 93 and 101, respectively) were included in the study. Patients with metabolic syndrome had lower oxygen saturation at the time of admission (88.76 vs 93.66 p <0.0001), higher neutrophil (5.85 vs 4.81 p = 0.02) and CRP levels (88.36 vs 62.93 p = 0.009) and COVID 19 involvement was more common in lung tomography (12.3 vs 7.7 p <0.0001). Total length of stay (12.3 vs 6.5 days p <0.0001) and clinical length of stay (7.8 vs 5.9 days p = 0.003) were longer in patients with metabolic syndrome. Requirement of intensive care (45.2% vs 4.9% p <0.0001) and mortality rates (24.7% vs 0.9% p <0.0001) were higher in patients with metabolic syndrome. Presence of metabolic syndrome (OR 32.86, 95% CI 4.34 to 249 p<0.05) were significantly associated with increased mortality. Discussion and conclusion: Our results demonstrated that patients with metabolic syndrome that were hospitalized with COVID 19 pneumonia had significantly higher mortality and intensive care requirement. They have lower oxygen saturations, higher CRP levels and more widespread radiological involvement. Keywords: Covid 19 - Metabolic syndrome – Pneumonia - Mortality