Chronic constrictive pericarditis (CCP) due to tuberculosis has high morbidity and mortality in the periopeartive period following pericardiectomy because of left ventricular (LV) dysfunction. Brain-type natriuretic peptide (BNP) is considered a marker for both LV systolic and diastolic dysfunction. We undertook this prospective study in 24 patients, to measure the BNP levels and to compare it with transmitral Doppler flow velocities, that is, the E/A ratio (E = initial peak velocity during early diastolic filling and A = late peak flow velocity during atrial systole), as a marker of diastolic function and systolic parameters, pre- and post-pericardiectomy, at the time of discharge. The latter parameters have been taken as a flow velocity across the mitral valve on a transthoracic echo. There was a significant decrease in the mean values of log BNP (6.19 +/- 0.33 to 4.65 +/- 0.14) (P = 0.001) and E/A ratio (1.81 +/- 0.21 to 1.01 +/- 0.14) (P = 0.001) post pericardiectomy, with a positive correlation, r = 0.896 and 0.837, respectively, between the two values at both the time periods. There was significant improvement in the systolic parameters of the LV function, that is, stroke volume index, cardiac index, systemic vascular resistance index, and delivered oxygen index. However, no correlation was observed between these values and the BNP levels. We believe that BNP can be used as a marker for LV diastolic dysfunction in place of the E/A ratio in patients with CCP, undergoing pericardiectomy. However, more studies have to be performed for validation of the same.