Carbenoxolone Sodium (CS), a chemical derivative of liquorice is known to be associated with hypertension, increased sodium retention and hypokalemia. The present studies describe the effects of CS on the renal actions of the glucocorticoids Corticosterone (B) and Cortisol (F) on sodium and potassium in adrenalectomized male rats. B (50, 100 and 500 micrograms/rat) and F (1 mg/rat) were found to possess no intrinsic antinatriuretic activity which is represented by a decrease in the Na+ to creatinine ratio; while only B (500 micrograms/rat) demonstrated kaliuretic effects as indicated by an increase in K+ to creatinine ratios. B and F showed very significant antinatriuretic and kaliuretic properties following pretreatment with CS (2.5 mg/rat). CS alone was not found to be antinatriuretic at this dosage. Further experiments demonstrated that lower dosages of CS (500 and 1,000 micrograms/rat) also cause B to exhibit Na+ retaining and K+ excreting properties. Thus, we have demonstrated that pretreatment with CS can confer mineralocorticoid-like activity upon the glucocorticoids B and F.