In conclusion, we believe that the baboon offers many advantages as an experimental animal to study vascular disease, thrombus formation and dissolution, the effects of mediating variables, and the relative efficacy of therapeutic interventions. Each specific application for testing therapeutic agents may require testing in different model systems. For example, the AV vascular graft model is efficient, cost effective and well adapted to study interventions for acute arterial thrombosis. As the antithrombotic products of genetic engineering and molecular biology emerge, it will be increasingly important to have relevant, reproducible, and quantitative approaches to evaluate their effects in vivo.