Aims: To study the efficacy of aprotinin in controlling bleeding from parenchymatous organ trauma. Materials and Methods: Thirty-two gruinea pigs were utilized in 4 groups. While group 1 was control, group 2 was sham operated. Standard liver resection was performed in groups 3 and 4 and aprotinin at dose of 10.000 KIU/kg was infused via jugular catheter ten minutes before the liver resection in group 4. Bleeding amounts were recorded in these groups during 1 hour with weighing the sponges placed into abdomen. Histopathologic, hematologic and fibrinolytic parameters were measured. Results: The amount of bleeding in the liver resection group was 5.9142±0.67 gr whereas it was significantly lower with 3.1875±0.89 gr in the aprotinin administered group (p<0.05). In the aprotinin group the changes in the levels of hemoglobin and hematocrit were also statistically significant (p<0.05). There was no significant difference between the levels of fibrinogen, but there was an increase in euglobulin lysis time (ELT), decrease in tissue plasminogen activator activity and decrease in the level of D-Dimer (p<0.05). Conclusions: This study demonstrated that aprotinin can decrease the amount of bleeding in parenchymatous organ trauma while suppressing fibrinolytic activity. With aprotinin treatment, there were significant decreases in the levels of D-Dimer, significant reductions in tissue plasminogen activator activity and significant lengthening of the euglobulin lysis time, whereas PT-aPTT levels did not change.