AbstracBackground: Acute normovolaemic haemodilution (ANH) is one of the types of autotransfusion which can be used as an alternative method of replacing lost blood during surgery. Normovolaemia has to be maintained during ANH by administering sufficient volume of haemodiluents either crystalloids or colloids. Aim: To compare prospectively the effects of two haemodiluents, Crystalloid (Ringer lactate) and Colloid (Polygeline) in moderate Acute Normovolaemic haemodilution (ANH). Methodology: 50 patients(ASA physical status I or II) undergoing elective gynaecological surgeries with an estimated prediction of blood loss from 500-750ml in each patient were divided into two groups of 25 each. In Group R – Ringer lactate in the ratio of 3:1 and in Group H –Polygeline (Haemaccel) in the ratio of 1.5:1 were used during haemodilution. Heart rate, systolic BP, diastolic BP, SPO2 and Haematocrit were observed before and after haemodilution, before and after retransfusion of the blood. All the data were analyzed using Student’s ‘t’ test and P values < 0.05 were taken to be significant. Results: During all the stages there were no statistical differences in heart rate, systolic BP, Diastolic BP, SPO2, Haematocrit and surgical blood loss between the two groups. Conclusion: We conclude that during moderate acute normovolaemic haemodilution(ANH) either Ringer’s lactate or Polygeline(Haemaccel) can be used as replacement fluid as both are comparable in terms of haemodynamic stability, oximetric and haematological profiles.