In 1913, Pasteau and DeGrais reported a few cases of cancer of the prostate and bladder in which truly striking results had been obtained by the use of radium introduced into the urethra through an ordinary catheter (Fig. 1). This led me, in 1914, to procure some radium and to try it in certain selected cases. It soon became evident that for accurate work much more exact methods and special instruments would be necessary, and in the machine shop of the Brady Institute I set about to design and construct instruments to meet the varying needs in vesical and prostatic cancer. The accompanying illustrations show the different models so well that little description is necessary. The small, straight cystoscope which is used in my cystoscopic rongeur (Fig. 2) was used as a basis around which to construct the various radium instruments. Radium Instrument 1 (Figs. 3 and 4) carries the