Purpose: Community-acquired pneumonia (CAP) is a potentially lethal lower respiratory tract infection affecting children all over the world. In this study, we aimed to evaluate plasma kallistatin levels in children at the time of admission and on the fourth day of treatment to determine if this is effective in deciding whether to hospitalize patients and to assess the response to treatment in patients with CAP. Methods: This prospective case/control study was conducted between November 2015 and May 2016 at Erciyes University School of Medicine, in the Department of Paediatric Pulmonology. Fifty-three patients, who were diagnosed with CAP with clinical and radiological findings, were included in the study. The patients were divided into various subgroups such as inpatients, outpatients, those with complications, those without complications, and dead patients. The levels of kallistatin were compared between the control group and the patient group. Results: A total of 53 children with a diagnosis of CAP and 55 healthy children were enrolled in the study. The plasma kallistatin level of CAP patients at admission was significantly higher than that of the control group [1.6 (1.2-2.9) ng/mL], [0.9 (0.7-1.1) ng/mL] (P<0.001). The patient group was divided into 3 subgroups: those with complications, those with no complications, and those who died. In patients who were hospitalized, who died, and who were in need of mechanical ventilation (MV), kallistatin levels were significantly higher than in the other patients (P=0.027 for hospitalization; P=0.022 for exitus; and P=0.008 for MV) at the time of diagnosis and on the fourth day of treatment. Conclusion: A higher plasma kallistatin level was found to be significant in CAP. Patients with high kallistatin levels should be carefully monitored for hospitalization and for unwanted side effects such as MV need and death.