Surprisingly large quantities of organic phosphorus in the urine have been recorded in certain pathological conditions. Amounts approaching 1 gm. in 24 hours have been reported and numerous determinations varying from 0.1 to 0.3 gm. may be found. The excretion of so much organically combined phosphorus would constitute a striking abnormality and would bare careful investigation in the light of recent advances in our knowledge of the role played by phosphorus compounds in nerve, muscle, and bone physiology. Several investigators did not note these great quantities of urinary organic phosphorus. However, their studies did not include many pathological conditions. A more extended search was, therefore, made to find instances of such an abnormal state.The organic phosphorus was separated from the inorganic by treating the urine with Mathison's1 magnesium citrate mixture. The filtrate was tested for complete precipitation by Scott's2 reagent and an aliquot digested with sulphuric and nitric acids. The digest w...