The old time term "uric acid diathesis" was an elastic expression, embracing such different conditions as gout, chronic rheumatism, uratic calculus, obesity and certain nephritides. In the light of more recent knowledge, the meaning of the term has been gradually narrowed until at the present time it includes only those diseases or clinical syndromes which are more or less intimately connected with a pathologic purin metabolism. It will be our purpose in this paper to consider those disease types which fall under this heading, to point out, as far as is possible, wherein lies the departure from normal metabolism, to formulate any general rules which can serve as a basis for rational treatment, and to bring out such facts as are known concerning special or specific therapy. One of the most striking conditions in the uric acid diathesis is the occurrence of an increase in the uric acid content of