Recently there has been increasing concern over transfusion-related diseases, especially acquired immune deficiency syndrome (AIDS). The authors therefore investigated the efficacy of lactated Ringer's solution (LRS) alone as compared with blood plus LRS resuscitation on body weight change and mortality rate after severe trauma-hemorrhagic shock. Rats, 250 to 310 g (n = 85), had a midline laparotomy performed (i.e., trauma induced), the incision was closed, and a carotid artery, jugular vein, and femoral artery were cannulated. The unrestrained, nonheparinized rats were allowed to recover from anesthesia and were bled within 10 minutes to a mean arterial pressure (MAP) of 40 mmHg. This MAP was maintained by removing more blood until the animal was unable to compensate (maximal bleedout; MB). The MAP was further maintained at 40 mmHg by returning fluid (LRS) until 50% of the MB volume (MBV) was returned. The rats were then resuscitated: group 1 with LRS 4 times the MBV; group 2 with 5 x LRS; group 3 with the shed blood returned + 2 x LRS. There was no difference between the groups in the initial weights, MAP, or hematocrit (Hct), percentage of blood volume removed, time to MB, or time to end of hemorrhage. The final Hct and MAP were higher in group 3 (p < 10-6) than in either of the other groups. Body weight gain was greater in group 2 compared with either of the other groups (p < 0.05) on day 1 after hemorrhage because of edema, but no differences were seen on subsequent days. There were no differences in the survival of animals in the different groups. These results suggest that there should perhaps be a higher threshold for blood transfusion in the management of severe trauma-hemorrhagic shock than is currently practiced.