OBJECTIVE: Patients on long-term anticoagulation requiring interruption of therapy for a surgical procedure historically have been hospitalized to receive "bridging therapy" with continuous infusion intravenous unfractionated heparin (UFH). Recently, low-molecular weight heparins such as enoxaparin have been reported to have comparable safety and efficacy in this indication, and can be administered on an outpatient basis. The objective of this study was to compare the costs of bridging therapy with enoxaparin versus UFH in this patient population. METHODS: We conducted a cost-minimization analysis of bridging therapy from the perspective of a third-party health insurer. Patient treatment protocols were set forth to reflect current clinical practice. Bridging therapy was assumed to take place over an eight-day period, reflecting three preoperative days, one day of surgery, and four postoperative days. Three alternative bridging strategies were considered: (1) UFH 30,000 units/day administered in hospital; (2) enoxaparin 1.0 mg/kg self-administered twice-daily by the patient at home; and (3) enoxaparin 1.5 mg/kg administered once-daily in the patient's home by a visiting nurse. Various secondary sources were used to estimate the costs of drug acquisition, ancillary supplies, provider services, and hospitalization. Analyses were performed for day surgery, surgery requiring overnight stay, and surgery requiring a stay of 4+ days. RESULTS: Bridging therapy with UFH in hospital costs $4,397 per patient for day surgery, $3,818 for procedures requiring an overnight stay, and $2,080 for procedures requiring a stay of 4+ days (2001 US$). Corresponding cost estimates for patient-administered enoxaparin are $663, $673, and $743. Cost estimates for nurse-administered enoxaparin are $990, $935, and $771, respectively. CONCLUSIONS: Bridging therapy with enoxaparin at home whether patient-administered or nurse-administered is substantially less costly than bridging with UFH in hospital. The magnitude of cost savings is highest for day surgery and lowest for surgeries requiring a prolonged recovery in hospital.