Introduction of phytiexdizone-exdisterone (0.5 mg/100 g) to rats for 7 days is shown to be attended by an accelerated body weight gain and also by a rising weight of the liver, heart, kidneys and musculus tibialis anterior. In these organs the total amount of protein increases. All of the above-stated changes are more marked when the substance is given to growing rats (70--80 g). In experiments on castrated sexually immature rats the androgenic action of exdisterone, unlike that of methandrostenolone, is not demonstrable.