For more than 50 years, Coumadin was the dominant warfarin sodium product available in the United States. The approval of generic formulations of warfarin sodium has generated much debate over the therapeutic equivalency and the appropriateness of therapeutic substitution for the innovator product. Despite an AB rating by the Food and Drug Administration (FDA) and recent studies documenting successful switch programs from brand name to generic, much controversy remains concerning the approval process for generic formulations and whether substitution for the innovator product is appropriate. The healthcare professionals affected most by these questions are those working in specialized anticoagulation clinics. We conducted a survey to determine the current practice, experience, and views of healthcare professionals practicing in anticoagulation clinics regarding the substitution of generic products. In addition, the survey sought to identify factors important to healthcare professionals when deciding to use generic or brand name warfarin. Many of these healthcare professionals, primarily pharmacists and nurses, are resistant to generic warfarin substitution and prefer to use the innovator product. These perceptions may change over time as additional data showing comparative therapeutic outcomes between generic and brand name formulations are published.