Asthma is one of the most common childhood non-infectious diseases. Corticosteroids are important medicine in the treatment of asthma. According to the international guidelines, systemic administration of corticosteroids is the international standard in the treatment of acute exacerbations of asthma. Certain diseases (bacterial infections, viral infections, tumor diseases, etc.) can cause elevation of leukocytes in the blood above normal levels, as well as the certain medicine such as heparin, lithium, corticosteroids. The aim of this study is to examine the effect of systemic administration of corticosteroids on leukocyte values in pediatric asthma patients treated at the Srebrnjak Children's Hospital in 2018. Information from the Hospital Information System was analyzed, with the prior approval of the Ethics Committee of the Srebrnjak Children's Hospital. The inclusion criteria were met by 34 subjects. Analyzed variables included sex, body height, body weight, oxygen saturation, and leukocyte count. The study results indicate a statistically significant difference in leukocyte values measured before and after the therapy with systemic corticosteroids. There was also a statistically significant difference in the oxygen saturation variable before and after the therapy, which is an expected result given the effect of systemic administration of corticosteroids in the treatment of acute exacerbation of pediatric asthma. Age positively correlated with body weight and height, body weight and height positively correlated with each other, as well as with leukocyte count before and after the therapy with systemic corticosteroids. The abovementioned correlations were expected considering the effect of systemic corticosteroids on leukocyte count and oxygen saturation, as well as their use in the treatment of acute exacerbation of asthma. Key words: