BACKGROUND: Assessment of diastolic function has not been described after repair of total anomalous pulmonary venous drainage (TAPVD), but studies of exercise capacity demonstrate impaired performance in this population despite normal systolic function. We postulated that diastolic impairment might contribute to this finding. METHODS: We analyzed echocardiographic variables from 28 patients with repaired TAPVD and compared these with data from 32 healthy controls (normals) and 21 subjects with repaired transposition of the great arteries (TGA). RESULTS: Left ventricular (LV) end-diastolic volumes were smaller in the TAPVD group (median, 50 mL/m(2) compared with a median of 64 mL/m(2) in TGA and 67 mL/m(2) in normals; P < .001 in each case). LV diastolic function in the TAPVD group was impaired. Mitral early to late ratio was increased (median, 2.7 in TAPVD compared with a median of 1.9 in TGA [P = .047] and 2.1 in normals [P = .021]). LV isovolumic relaxation time was reduced (median, 50 milliseconds in TAPVD compared with a median of 70 milliseconds in both TGA and normals; P < .001 in each case). Late diastolic and systolic tissue Doppler velocities were lower and the E/e' ratio was higher in the TAPVD group. CONCLUSIONS: Patients with repaired TAPVD are usually regarded as having excellent outcomes, but the finding of LV diastolic dysfunction in this population warrants more careful follow-up. We postulate that the diastolic impairment in these patients is the result of relative unloading of the LV during early cardiac development. These findings may also have implications in considering therapeutic approaches for hypoplastic ventricles in attempting to achieve biventricular repair.