Objective. To study specific features of potassium metabolism and myocardial damage markers in the children with bronchial asthma, depending on the level of BA control. Materials and methods. Comprehensive examination was carried out in 189 children with persistent BA aged 6-17 years: group 1 consisted of 124 with uncontrolled course of the disease, group 2-30 patients with partially controlled BA and 35 patients with controlled BA. The comparison group consisted of 30 patients with controlled asthma without changes from the cardiovascular system. The unified flame photometry method with fluid analyzer FFA-1 was used to determine the erythrocyte potassium level. Total creatine phosphokinase level was estimated by UV-test. Creatine phosphokinase-MB level was determined by M-subunit immunoinhibition. Total lactic dehydrogenase-1 level was calculated by modified colorimetric method using an assay kit for colorimetric determination of total LDH. Serum LDH1 level was estimated by UV-method with the kit for determination of isoenzyme LDH1 activity. Results. In the children with UC BA serum K + and erythrocyte K + level was significantly lower compared to the children with PC BA, C BA, C BA with no changes in CVS and the control group. Total CPK and CPK-MB isoenzyme level in the children with UC BA, was significantly higher compared to those with PC BA, C BA, C BA without CVS changes and the control group. In the children with PC BA, total serum CPK level was also significantly higher compared to C BA (P = 0.007), C BA without CVS (P = 0.0002) changes and the control group (P = 0.001). Conclusion. Thus, the study demonstrated significant decrease of potassium level in blood serum and erythrocytes, twofold increase of total creatine phosphokinase and lactic dehydrogenase-1 isoenzyme levels, threefold increase in creatine phosphokinase-MB isoenzyme level, and one and a half time increase of total lactic dehydrogenase in the children with uncontrolled course of bronchial asthma.