We all recognise pain as one of the most important symptoms of arthritis, but it is not always present and we are not too clear how it happens. How is pain mediated? What are the anatomical and physiological mechanisms involved in its appreciation? This is an under-researched phenomenon but this lengthy review tries to give some perspective to it all. Perhaps we can moderate pain more effectively if we can synthetise compounds that specifically block substance P: the prospect of being able to do this effectively might give us a new therapeutic horizon.