AbstractBackground.Thromboembolism is a risk in major head and neck cancer surgery patients predisposed to thrombosis. This study was designed to determine whether enoxaparin (a low molecular weight heparin) administered prior to surgery induces perioperative bleeding.Methods.Forty patients scheduled for major cervicofacial cancer surgery were randomized in a double‐blind study to receive either 20 mg enoxaparin or placebo, 12 hours before surgery. Blood losses were measured at the end of surgery and 6 hours later.Results.Bleeding was equal in the placebo group and in the enoxaparin group, with losses of 648 ± 106 mL and 602 ± 106 mL (p= 0.76), respectively. Six hours after surgery, blood collected was 159.3 ± 25.7 mL in the placebo group vs 151.4 ± 21 mL in the enoxaparin group (p= 0.81).Conclusion.Preoperative administration of enoxaparin is safe in head and neck cancer surgery, but further studies are required to evaluate its efficacy in preventing thromboembolism. © 1995 Jons Wiley&Son