of sodium and aldosterone possessed by amphenone. Thyroid function also was not affected. SU 4885 is much the less toxic of the two drugs, gastric disturbances being the only consistent symptom. The excessive drowsiness which severely limits the use of amphenone did not occur.Although the action of SU 4885 on other adrenal steroids, notably oestrogens, has not yet been studied, the relatively large doses required to suppress hydrocortisone together with the formation of 1 l-deoxyhydrocortisone and probably deoxycortone do not indicate that this particular drug has immediate clinical application as an adrenal inhibitor. On the other hand, it seems likely that further compounds will be elaborated by means of which selective inhibition of adrenal enzyme systems may be satisfactorily achieved in patients.Summary The effect of a new adrenal inhibitory compound, SU 4885, has been studied in eight patients. Inhibition is directed particularly at adrenal steroid 1 1,3-hydroxylation, so that 11-deoxyhydrocortisone (compound S) and its urinary metabolite tetrahydro-S were found in relatively large quantities in blood and urine. In sufficient dosage, orally or intravenously, SU 4885 appeared capable of reducing the levels of hydrooortisone and its urinary metabolites.The toxicity of SU 4885 was significantly less than that of amphenone B.