The establishment of syphilitic disease of the kidneys on a firm clinical basis is of considerably later date than any of the other syphilitic visceropathies. This is no doubt true because of the great difficulty of differentiating between the end-result of syphilitic disease and the common forms of fibrosis of the kidneys, whether the latter be produced by old age, disease or both. Moreover, the differentiation between renal irritation due to syphilitic processes and the various other types of nephritis constitutes a second difficulty in establishing a pathologic diagnosis. That nephritis occurred in the course of a syphilitic's life, however, was recognized by clinicians before the establishment as an entity of true syphilitic renal disease. This nephritis, however, was interpreted as the effect of mercury rather than as in any way related to the disease process. In 1859, Rayer placed syphilitic kidney disease on a firm basis. After him Virchow,