The emphasis on medical technology assessment has been on new and/or high-unit-cost technologies. It is the premise of this proposal that existing low-unit-cost high-volume technologies employed in ambulatory care constitute an important use of medical resources. This pilot study will: (a) derive data associating specific technologies with specific clinical problems in a number of ambulatory sites using COSTAR systems and test the derived data against alternate sources representing national samples; (b) use average national charge data to identify those technologies arising from specific complaints and diagnoses that cause the largest aggregate charges; (c) search the literature for cost-effectiveness and other measures assessing diagnostic and therapeutic technologies for technologies associated with clinical problems covering the highest 20% of aggregate charges that are high on the list of common ambulatory problems; and (d) test methods for identifying new ambulatory care technologies before they become established medical practice. This pilot study is intended to provide the basis for deciding whether the assessment of diagnostic and therapeutic technologies for primary care should be on the national agenda, to identify the directions and tools for undertaking such a national study, and to establish methods, information resources, and priorities for a national study.