We hypothesized that diastolic dysfunction may be an earlier phenomenon than systolic dysfunction in patients with HbSS anemia. Indices of pulsed Doppler wave analysis of the mitral valve were obtained in 23 patients with HbSS (age 4-17yr, mean 11yr) in resting steady state & 32 age matched control subjects (age 4-16yr, mean 9.4yr). Diastolic function was assessed by the indices listed in the table. Systolic function(Shortening fraction, SF), LV dimensions, LV mass and cardiac Indices were also calculated. Results as compared to control values (Mean ± S.D): 11 of 23 (48%) patients with HbSS had diastolic dysfuction. 4 of 11 patients had a restrictive pattern (Group A) with reduced early diastolic deceleration time(<100ms) and decreased A area. The other 7 patients showed impaired filling patterns (Group B) characterized by prolonged deceleration time (>160ms), decreased E/A area & E/A velocity, prolonged IVRT (Iso-volumic relaxation time). The increase in E area was proportionately less than that of A area as evident in the E/A area. The remaining 12 patients had measurements not different from control except for increased peak E velocity like those in Groups A & B suggesting increased preload. All patients with HbSS had normal SF but increased LV systolic & diastolic dimensions, septal and free wall thickness, LV mass and cardiac indices. Conclusion: LV DF is altered in a significant proportion of patients with HbSS and may be an early indication of myocardial dysfunction in these patients in the presence of normal SF.