Background: Transesophageal echocardiography (TEE) has not been compared to transthoracic echocardiography (TTE) for assessment of left ventricular diastolic function (LVDF). Left ventricular diastolic dysfunction is common in systemic lupus erythematosus (SLE), a disease model of premature myocardial disease., Methods: 66 patients with SLE (mean age 36±12 years, 91% women) and 26 age-and-sex matched healthy volunteers (mean age 34±11 years, 85% women) underwent TEE immediately followed by TTE. From basal four-chamber views, mitral inflow E and A velocities, E/A ratio, E deceleration time, isovolumic relaxation time, septal and lateral mitral E' and A' velocities, septal E'/A' ratio, mitral E to septal and lateral E' ratios, and pulmonary veins systolic to diastolic peak velocities ratio were measured. Measurements were averaged over 3 cardiac cycles and performed by 2 independent observers., Results: LVDF parameters were worse in patients than in controls by TEE and TTE (all p≤0.03). Most LVDF parameters were similar within each group by TEE and TTE (all p≥0.17). By both techniques, mitral E and A, mitral and septal E/A ratios, septal and lateral E', septal and lateral E/E' ratios, and average E/E' ratio were highly correlated (r=0.64-0.96, all p≤0.003); E deceleration time, isovolumic relaxation time, and septal A' velocities were moderately correlated (r=0.43-0.54, all p≤0.03); and pulmonary veins systolic to diastolic ratio showed the lowest correlation (r=0.27, p=0.04)., Conclusion: By TEE and TTE, LVDF parameters were worse in SLE patients than in controls; and in both groups, LVDF parameters assessed by TEE and TTE were similar and significantly correlated., Competing Interests: Conflicts of Interest None.