The aim of this study was to evaluate diastolic function in pediatric cardiac transplant recipients free of acute rejection using tissue Doppler. E' and A' velocities at the mitral, septal, and tricuspid annuli in 31 pediatric heart transplant recipients free of acute rejection were compared with 28 controls and with previously published pediatric normative data. E' velocities were lower in the transplant group at the mitral (0.13 +/- 0.04 vs. 0.2 +/- 0.04 m/s, p < 0.0001), septal (0.1 +/- 0.03 vs. 0.14 +/- 0.03 m/s, p = 0.001), and tricuspid annuli (0.1 +/- 0.04 vs. 0.17 +/- 0.04 m/s, p < 0.0001). A' velocities were also lower in the transplant group at the septal (0.04 +/- 0.01 vs. 0.06 +/- 0.01 m/s, p = 0.001) and tricuspid annuli (0.06 +/- 0.02 vs. 0.1 +/- 0.03 m/s, p < 0.00001). E' and A' were abnormally low at the mitral annulus in 31% and 13%, septal annulus in 50% and 21%, and tricuspid annulus in 63% and 36% of the subjects, respectively. Abnormalities in tissue Doppler-derived diastolic myocardial velocities are common in pediatric cardiac transplant recipients free of acute rejection.