Following the method of Osborne, Mendel and Ferry, which compares average gain per gm. of protein ingested, 17 products, divided into the following groups, were analyzed:[long dash](1) various breads commonly consumed in Poland, (2) experimental breads, (3) soy-bean flour and baker''s yeast. A supplementary relation exists between the proteins of white wheat flour and soy-bean flour, when mixed in the approximate proportions of 9 to 1 and 4 to 1 and also between the proteins of white wheat flour and baker''s yeast. A similar relation may also exist between the proteins of rye flour and soy-bean flour. N of crust had a lower biological value than that of crumb or of whole bread.