During the past three years we have carried out about 180 renal dietary tests and blood analyses. Most of the cases were diagnosed nephritis or arteriosclerosis, though a number of other diseases have been included in the tables. The routine employed was as follows: The blood for analysis was collected before breakfast. The patients were in bed during the dietary test. They received a uniform quantity of water and food. In most instances the Mosenthal1modification of the Hedinger and Schlayer2diet was administered. The urine was collected in two hour periods from 8 a. m. to 8 p. m., and in one period from 8 p. m. to 8 a. m. Recently Mosenthal3and Schlayer and Beckmann4compared the effect of a low protein or bland diet with that of the usual test diet. The former author found that both had approximately the same effect on the urine. Schlayer