These volumes contain the papers which were presented at the Third International Symposium on Purine Metabolism in Man held in Madrid (Spain) in June, 1979. The previous meetings in the series were held in Tel Aviv (Israel) and in Baden (Austria) in 1973 and 1976, respective1y. The proceedings were also published by Plenum. Knowledge of the pathophysio1ogy of the purines has developed greatly since the 1950's when it was main1y re1ated to c1inica1 gout, and it is now relevant to many fie1ds of Medicine and Biology. These volumes include papers reporting new work on clinical gout and uro1ithiasis as we11 as on some of the subjects which have featured prominently in the previous volumes, including: regulatory aspects of the intermediary metabolism of purines and re1ated com- pounds, enzymology, methodology, and the resu1ts of mutations which affect purine metabolism. However, there have been many new develop- ments during the last three years and the scope of the communications reflects not only increasing depth of know1edge, but also a widening of the field. This publication has clinical and fundamental imp1i- cations for internal medicine, pediatrics, uro1ogy, biochemistry, immunology, genetics, and oncology.