Traditionally, patients suspected to have lower-extremity deep vein thrombosis have undergone venography, which is invasive, is expensive, and may cause deep vein thrombosis in healthy individuals. Recent studies have shown the safety and efficacy of alternative noninvasive approaches that employ impedance plethysmography or real-time ultrasonography. We compared these tests using decision analysis to model the consequences of 24 different management strategies for ambulatory patients suspected to have deep vein thrombosis. We also calculated the incremental cost per additional life saved for each strategy. Our analysis revealed that the optimal approach was to perform real-time ultrasonography followed by anticoagulation therapy if deep vein thrombosis is found. This approach was both effective and cost saving compared with no testing or treatment. Serial follow-up studies of patients whose initial study suggested no DVT saved additional lives, but at a cost of $390,000 per each additional life saved for patients with one follow-up study and $3.5 million per each additional life saved for patients with a second follow-up study. Venography should play a limited role in the contemporary evaluation of patients suspected to have deep vein thrombosis. Future research should focus on the determination of clinical predictors of patients who should undergo serial examinations.