Radioactive myo inositol was injected intraperitoneally into nephrectomized rats. The radioactive material present in liver, spleen, brain, heart, diaphragm, seminal vesicle, coagulating gland, prostate, epididymis, vas deferens and testis was shown to consist exclusively of myo inositol and its derivatives, as shown by paper chromatography of hydrolysates and trichloroacetic acid extract of these tissues. Radioactive myo inositol was accumulated rapidly within 1 h by the thyroid, coagulation gland and seminal vesicle. Other tissues, such as pituitary, prostate gland, liver and spleen, concentrated myoinositol less activity. The muscle tissues studied (diaphragm and heart) concentrated little inositol, whereas brain, testis, and epididymal fat pad did not concentrate in at all. The lipid fractions of liver contained most of the radio labeled myo inositol. In the other organs most of the radioactivity was found in the aqueous trichloroacetic acid extract, largely as free myo inositol.