Constrictive Pericarditis (CP) is a curable and reversible form of severe diastolic heart failure. We aimed to investigate the diagnostic accuracy of published echocardiographic Mayo Clinic Criteria in differentiating 107 patients with surgically proven CP from 30 patients with restrictive cardiomyopathy due to cardiac Amyloidosis. Five principal echocardiographic and Doppler variables were remeasured on preoperative transthoracic echocardiogram namely (1) respiration-related ventricular septal shift; (2) respiratory variation in mitral inflow E pulsed Doppler velocity; 3) tissue Doppler medial mitral annular e’ velocity; (4) ratio of medial mitral annular e’ to lateral mitral annular e’ velocity; and 5) hepatic vein (HV) pulsed Doppler diastolic flow reversal ratio. Etiology of CP included viral/idiopathic or autoimmune (75%), postcardiac surgery (13%) and postradiation (7%). Univariate logistic regression analysis showed that (1) respiration related ventricular septal shift, (2) percentage change in Mitral E velocity, (3) medial e’ velocity ≥9 cm/sec, (4) medial e’/lateral e’ ratio ≥0.91, (5) HV diastolic reversal ratio ≥0.79 were associated with the diagnosis of CP. Multivariable logistic regression analyses showed that medial e’ velocity ≥9 cm/s was independently associated with the diagnosis of CP. Respiration related ventricular septal shift had the highest sensitivity, whereas medial e’ velocity ≥9 cm/s has the highest specificity to diagnose CP (Areas under curves 0.99, p 0.001). Combining respiration related ventricular septal shift with medial e’ velocity ≥9 cm/s gave a desirable sensitivity (80%) and specificity (92%). Adding reversal ratio to this combination further increased the specificity (97%) but dropped the sensitivity (70%) to diagnose CP.