The aim of the study was to determine N-terminal proB-type natriuretic peptide (NT-pro-BNP) value in assessment of right ventricular function in children after Tetralogy of Fallot (TOF) correction. Methods: In 20 patients after TOF correction aged from 10 to 17 years NT-pro-BNP level and echocardiography were performed. In the control group NT-pro-BNP level was assessed. Results: The mean values of NT-pro-BNP level in the study and control group were respectively 11,0 +/- 12,0 fmol/l and 5,4 +/- 7,5 fmol/l (p<0,05). Right ventricular diastolic diameter ranged from 96,7% to 200% (mean 142,2 %) of limit and correlate positively with follow–up time (p=0,004, r=+0,353). Severe pulmonary regurgitation(PR) was visualized in 9 and mild/moderate PR in 11 patients. Statistically significant differences in NT-pro-BNP levels between children with severe PR and mild/moderate PR were detected (mean values 18,6+/-15,0 fmol/l vs 4,2+/- 3,9 fmol/l, p<0,05). In patients repaired with transannular patch the mean value of NT-pro-BNP level was higher than in children operated on without transannular patch (18,3+/- 16,5 fmol/l vs 6,8 +/- 7,9 fmol/l), (p<0,05).Right ventricular diameter correlated positively with NT-pro-BNP values (p<0,05, r=+0,50). Conclusions: The NT-pro-BNP level in patients after TOF correction is higher than in healthy children. NT-pro-BNP level is higher in children with right ventricle function disturbances expressed by the level of pulmonary regurgitation and value of right ventricle diameter. The NT-pro-BNP level is higher in children repaired with transannular patch than in children operated without transannular patch.