This prospective study was accomplished with 14 patients, 10 women and 4 men, where some pre-, intra- and immediate postoperative parameters of hemostasis were analyzed and compared to a control group of normal individuals. The patients included in this study were admitted to the Hospital das Clinicas at Unicamp in the 1990-1993 period. All the accepted patients have had their latest bleeding at least 30 days before surgery, therefore, after the acute bleeding phase, because in this phase there are alterations in hemostasis. In this period only dipyrone was used in all patients as analgesics and antipyretics. Opiates were used in all the anesthetic proceedings. The following parameters were determined: coagulation; prothrombin time, (PT), thrombin time, (TT), activated partial thromboplastin time, (APTT), platelets (PQ), fibrinogen, (FG) factor V, (F V), protein C, (P C), protein S (PS), antithrombin III (AT III); fibrinolysis, plasminogen (PLG), C 1 inhibitor (C 1), alfa 2 macroglobulin (A2M), prekallikrein (PK), euglobulin lysis time (ELT), lysis area in fibrin plates (LAFP), in 5 of these 14 patients. Activity of both plasminogen tissue activator (t-PA) and plasminogen activator inhibitor (PAI-1) were also determined. For analyze the hepatic function pre-albumin (PRE ALB) was determined. In this study, the analysis of LAFP and ELT in the different surgical times suggests that the patients submitted to cerebral aneurysm surgery are head to hypofibrinolysis from the intraoperative to the immediate postoperative period and this evidence do not related whit PAI-1.42131-6