Aims: Tissue Doppler imaging has been recently used to evaluate ventricular function in patients with β thalassemia. In clinical practice, serum ferritin is commonly used to assess the severity of iron overload. The aim of this study was to determine which Doppler findings correlated with serum ferritin. Methods and results: Thirty-one pediatric patients with transfusion-dependent β thalassemia with normal LVFS were evaluated. Seven patients with serum ferritin <2500 ng/ mL, 13 patients with serum ferritin 2500-5000 ng/mL, and 11 patients with serum ferritin >5000 ng/mL were studied. Diastolic dysfunction was absent in all patients with serum ferritin <2500 ng/mL, and was present in all patients with serum ferritin >5000 ng/mL. Deceleration time (DT) has a significant correlation with serum ferritin (r = -0.59, p < 0.0001). Difference of pulmonary vein atrial reversal flow and mitral valve A wave duration (PVAR - MVA) and early ventricular filling velocity to early diastolic myocardial velocity ratio (E/Em) significantly correlated with serum ferritin (r = 0.49, p = 0.006; r = 0.56, p = 0.001, respectively). Conclusion: Decreased DT, increased PVAR-MVA duration, and increased E/Em ratio reliably reflected severe iron overload in pediatric patients with β thalassemia. Systolic and diastolic LV function is preserved in patients who have serum ferritin <2500 ng/mL. © The Author 2007.