Angiotensin II increases aldosterone production of isolated and superfused bovine adrenal glands. Indomethacin shows a bi-phasic effect on the production of the above-mentioned hormone, inhibitory at low doses (0,2 microgram/ml), stimulatory at high doses (5.0 microgram/ml). Preincubation with this drug impedes the increase of aldosterone production induced by angiotensin II. It is likely that the steroidogenetic effect of angiotnesin II is carried out through the PGs.