Introduction: This study aimed to investigate the relationship between community-acquired pneumonia severity and D-dimer levels in individuals older than 65. We also investigated the relationship between D-dimer levels and the adverse outcomes in patients with community-acquired pneumonia after excluding all other potential causes of high D-dimer levels. Materials and Methods: Patients older than 65 who were admitted to the emergency service of a tertiary chest diseases training and research hospital between January 1, 2019, and October 1, 2020, were evaluated. Patients who met the diagnostic criteria for community-acquired pneumonia were included. In clinically questionable cases of coexistence of pulmonary embolism and community-acquired pneumonia, D-dimer levels and pulmonary computerize tomography angiography or ventilation-perfusion scintigraphy were examined. Confirmed pulmonary embolism patients were excluded. Of 4,608 patients evaluated, 82 had a diagnosis of community-acquired pneumonia with no comorbidity. The severity of these cases was determined with the CURB-65 score and pneumonia severity index score. Results: The mean age of the cases was 73.83±6.67 years, while their gender was predominantly male (n=51, 62.2%). A statistically significant correlation was found between D-dimer levels and both the CURB-65 and pneumonia severity index high-risk groups (p=0.001 and p=0.001, respectively). The adverse outcomes were statistically higher in both the CURB-65 and pneumonia severity index high-risk groups (p<0.001). Conclusions: D-Dimer is an easy-to-interpret, fast, inexpensive, highly sensitive, and simple test widely used in clinics. We found that high levels of D-dimer can predict the need for intensive care unit care, disease severity, and mortality of elderly community-acquired pneumonia patients.