Hemodilution contributes significantly to transfusion requirements in patients undergoing CABG under CPB. We hypothesised that restriction of parenteral fluids in comparison to a liberal fluid administration policy leads to less use of packed red cells in CABG operations supported by cell salvage. After consent and approval, 130 patients operated under equal conditions were assigned prospectively and randomly either for a restrictive protocol for intravenous fluid administration (group A, 65 pts) or not (group B, 65 pts). Transfusion guidelines were common for the two groups. The volumes of intravenous fluids, priming, "extra" volume on pump and cardioplegic solution and the volume of urine were recorded. Net erythrocyte volume loss was calculated. The number of the transfused PRC was analyzed as a continuous variable. "Transfusion" was analyzed as a categorical characteristic. Significant difference existed between groups for the fluids administered intravenously until the initiation of CPB and for fluid balance after CPB. Intraoperatively transfused units were significantly lower in A (0.32 +/- 0.77 vs 1.26 +/- 1.05 u/per pt; p<0.0001). Transfused patients were also significantly lower in A (11/65 vs 44/65; p<0.0001). In both groups, the values of hematocrit were statistically decreased. The greatest difference compared to the preoperative values was observed after CPB (from 40.8 +/- 4.2 to 21.9 +/- 3.6 for A, and from 40.2 +/- 3.7 to 19.7 +/- 3.3 for B ; p<0.0001 for both). For these lowest values, significant difference existed between groups (p<0,001) while the difference in the hematocrit values to the end of operation was insignificant. Transfusion in ICU showed no significant difference among groups. Hours of mechanical ventilation in ICU were ranging from 5 to 29 (mean = 10.0, median = 9) for A and from 5 to 42 (mean = 14.8, median = 10) for B. Length of stay in ICU in nights for group A was ranging from 1 to 10 (mean = 2.7, median = 2) and for group B was ranging from 1 to 6 (mean = 3.5, median = 2). In conclusion, reduction of transfusions in CABG operations is feasible when a restrictive protocol for intravenous fluids is applied.