The purpose of this chapter is to discuss the use of hyperalgesia in the design of assays which quantitatively measure mild analgesic activity. The authors have taken the option not to attempt a comprehensive review of the literature but to comment critically on those contributions which relate directly to this purpose. Broad, comprehensive reviews on pain and analgesic testing are available (Winter, 1965; Swingle, 1974). To achieve their purpose, the authors have relied on their personal experience in the fields of inflammation and analgesic testing. It is their hope that this chapter will provoke new thinking and thus new research into the mechanisms of hyperalgesia and, additionally, lead to the more rational use of hyperalgesia and inflammatory phenomona in the design of mild analgesic assays.