The effect of prostaglandin E2 on the biosynthesis of corticosteroids was studied in intact rabbits and in the ones with vasorenal hypertension in different periods of its development (1st group) and in the animals subjected to a spurious operation (2nd group). Prostaglandin added to an incubation medium was found to produce in intact rabbits a significant depression of the 11-dehydrocorticosterone and cortisone biosynthesis from progesterone-C14. In rabbits operated upon (1st and 2nd groups) prostaglandin E2 brought changes in the production of corticosteroids no sooner than in 1 month after surgery. In rabbits with vasorenal hypertension brought about through unilateral constriction of the renal artery with an intact second kidney the content of the labeled 11-desoxycorticosterone and 11-desoxycorticosol materially decreased under the effect of prostaglandin E2, while the biosynthesis of the end fractions--11-desoxycorticosterone, aldosterone and cortisone, would gain in intensity. These changes preceded somewhat the most significant rise of the arterial pressure. In the rabbits spuriously operated upon prostaglandin E2 increased the production of corticosteroids and 11-dehydrocorticosterone, low at that time. It is presumed that prostaglandin E2 produces a regulating influence on the processes of the corticosteroids biosynthesis both in normalcy and in vasorenal hypertension.