Introduction. The term biomarkers or biological markers generally refers to proteins measured in the circulation (blood), whose concentration indicates some normal or pathological state or condition. The biomarker is objectively measured and evaluated as an indicator of normal biological processes or pharmacological responses to therapeutic interventions. One of these biological markers is C-reactive protein (CRP). Aim. To evaluate the efficiency of using adequate and appropriate biomarkers for diagnosis, treatment and monitoring of pneumonia in children. Methods. This study included 30 patients with diagnosed pneumonia, who were admitted at our Institute. Blood samples were taken prior to initiation of treatment in patients with pneumonia and 7 and 14 days after the treatment. The control group included physically active and healthy individuals without family history of disease, aged from 1 to 14 years. All the results of the biochemical analyses were within the reference values, and none of the control individuals received therapy. In our country, for serum C-reactive protein, as well as for other parameters that determine the diagnosis of the patient, we use a common method for determining normal values, by choosing a huge representative sample from the screening population, consisting of healthy individuals without any disease, especially with no sign of this disease (the children who should be checked up). Further, normal values obtained in this way are taken as reference values. Results. The average serum CRP protein levels prior to antibiotic therapy were the following: (1-2) x̄±sd =34.94±20.44 mg/L, (3-6) x̄±sd=68.20±10.87 mg/L, (7-11) x̄±sd=65.59±12.01 mg/L, whereas in patients with pneumonia after 7-day antibiotic treatment the values were the following: x̄±sd=24.64 ± 11.57 mg/L/x̄±sd =40.10±6.83 mg/L/x̄±sd=32.09±6.68 mg/L (Px̄±sd=6.80±1.14 mg/L/x̄± sd=7.20±0.82 mg/L/x̄±sd=8.10±0.89 mg/L (P Discussion and conclusion. This study is useful for showing the importance of C-reactive protein in serum for early diagnosis and follow-up of the pneumonia. CRP is very important as a biomarker, both from clinical and scientific aspect. It can be used for early rapid diagnosis, monitoring of pneumonia and can successfully be used in a large number of diagnosis. It opens new opportunities for further research in this field.