Normal saline 0.9% is the most commonly used crystalloid, isotonic and mainly distributed extracellular. This study compared normal saline 0.9% to haes-steril 6% and haemagel colloid solutions as regarding acid-base change after infusion in patients undergoing open abdominal surgeries. 60 patients were randomized to receive normal saline o.9% or haes-steril 6% or haemagel for a duration of 2-3 hours. Hemodynamic monitoring revealed significant increase in mean arterial blood pressure in haes-steril 6% group with no significant change in heart rate in any group. As regarding fluid balance, central venous pressure significantly increased in haes-steril 6% group with significant increase in urine output with normal saline 0.9% group. Dilutional acidosis had been resulted with all groups after end of therapy but significantly in normal saline 0.9% group in comparison to other groups. In conclusion normal saline 0.9%, haes-steril 6% and haemagel are considered safe on acid-base balance when given within normal dosage. Haemagel is the most safe as it insignificantly changed pH in comparison to normal saline 0.9% which decreased pH significantly more than haes-steril 6%. The significant change that occurred in acid-base balance with normal saline 0.9% was due to dilution of bicarbonate ion and decrease in strong ionic difference, while with haes-steril 6% was due to dilution of bicarbonate ion.