After knee replacement surgery, the use of continuous local anesthetic infusions in femoral and sciatic peripheral nerve catheters is an effective analgesic option. Limited data are available concerning the safety of peripheral nerve infusions in patients receiving low molecular weight heparin thromboprophylaxis. We report three cases of bleeding at femoral and sciatic catheter sites in patients receiving a single daily dose of enoxaparin (40 mg). In all cases, some bleeding was noticed before catheter removal; in one case involving catheter removal 3 h after enoxaparin administration, massive thigh swelling occurred. Physical therapy and discharge from the hospital were delayed in two cases but no other complications were seen. More data are needed to determine if it is necessary to use the same guidelines for managing peripheral nerve infusion catheters in patients receiving enoxaparin as with epidurals and other types of central nerve catheter infusions.