Several parameters of fibrinolytic and protein C pathways were evaluated in three groups of patients with high (HR), moderate (MR) and low (LR) postoperative thrombotic risk undergoing major gynaecological surgery. The HR and MR groups were subjected to low molecular weight heparin (LMW) prophylaxis. A significant increase in plasminogen activator inhibitor type 1 (PAI-1) antigen and activity levels was observed in the HR patient group in comparison with the MR and LR groups in the preoperative and early postoperative period. In all the groups studied, the maximum increase in the levels of PAI-1 was seen on day 1 after surgery. However, the D-dimeric levels reached the highest level on day 7. A significant increase in activated protein C:α1antitrypsin (APC:α1AT) complex levels was observed in the HR group in comparison with the LR group, and a strong decrease in protein C inhibitor in the early postoperative period was detected in all the groups. In spite of heparin prophylaxis, 2 HR patients were diagnosed as deep vein thrombosis (DVT) during the postoperative period. Both patients showed pre-operative levels of PAI-1 antigen or activity and APC:α1AT complexes above the mean + 1 SD of the pre-operative levels in the HR group. In conclusion, in HR patients a hypofibrinolytic and hypercoagulable state was detected in the pre-operative and early postoperative periods. The prophylactic LMW heparin dose used in the present report (20 mg/day × 7) was insufficient to prevent DVT in the HR group. At present our HR patients are given higher doses of LMW heparin (40 mg/day