Perioperative fluid therapy has a direct bearing on patient outcome and accordingly should be tailored individually. Thus the efficacy of HES 130/0.4 was compared to modified fluid gelatin for volume expansion during major abdominal surgery guided by transesophageal Doppler (TED). Fifty adult patients ASA physical status I-II undergoing major abdominal surgery were anesthetized with standard technique. In addition to basal fluid requirement, patients were randomly allocated into two equal groups (25 patients each) to receive 200 cc of either 6% HES 130/0.4 (HES group) or 3% modified fluid gel (GEL group) as intraoperative colloid replacement guided by TED. Heart rate, mean arterial blood pressure, central venous pressure, and Doppler derived measurements were recorded at the following timings: T1; after induction, T2; after skin incision, T3; two hours after that and T4; at the end of surgery. Fluid administration and transfusion requirements were recorded. Laboratory tests for hemostasis, hepatic and renal functions were continued till the fifth postoperative day. Both groups were comparable regarding Doppler derived data and fluid balance. Platelet count showed a significant drop (p<0.05) in group GEL in all postoperative days compared with baseline and with the group HES. Prothrombin time and INR showed a significant increase while prothrombin concentration showed a significant drop, throughout 5 postoperative days in group HES while in the 3 postoperative days in group GEL (p<0.05) but comparable between groups. Both groups showed postoperative drop in creatinine level and postoperative rise of liver function tests. HES 130/0.4 and modified gelatin have comparable fluid optimization effect guided by TED in major abdominal surgeries. HES 130/0.4 has a more favorable effect on platelet counts than modified gelatin.