A phase I SBIR program has been completed to design and develop a prototype system to permit convenient blood coagulation testing on freshly drawn samples from patients undergoing anticoagulant therapy. The study was based upon knowledge gained during the past two years with a sensitive monitoring system for blood coagulation reactions. A prototype reagent containing element together with an electronic measurement device was fabricated, tested, and analyzed for feasibility by Biotherm, Inc. This system has demonstrated the potential for rapid test turnaround time, greater convenience, and consequently better control of therapy in patients with thromboembolic disease. Further development during phase II will focus on: design and fabrication of preproduction prototypes; placement of these prototypes in clinical settings; acquisition of additional test data, including data obtained by nonlaboratory trained personnel such as nurses; and evaluation of feasibility of use in hospital and physicians' office applications. Testing in clinical environments will be performed in conjunction with the North Carolina Memorial Hospital, University of North Carolina, Chapel Hill.