Uncertainty regarding the optimal evaluation of suspected deep vein thrombosis (DVT) results in wide variations in practice, even within the same institution. To address variation in practice while maximizing the efficiency and quality of care, our institution developed a critical pathway guideline for the emergency department evaluation of patients suspected of having DVT. We present the critical pathway and the clinical rationale underlying its recommendations. The critical pathway was developed by a multidisciplinary team using chart review of practice at our institution, benchmarking at other institutions, and review and discussion of the medical literature. Consensus was achieved for the selection of ultrasound as the primary imaging test for all patients and for recommending initial doses of heparin sodium that are higher than the current norm at our institution to reduce the length of time required to achieve therapeutic anticoagulation. A total time for patient evaluation of 5 hours or less was established as the target. Controversy arose in two key areas: (1) the treatment of patients with normal ultrasound scans when high clinical suspicion for DVT exists and (2) the evaluation and treatment of suspected isolated calf-vein DVT. In its final form, the critical pathway recommendations seek to balance the benefits of standardization with the prerogatives of physicians to make decisions tailored to individual patients.