This controlled study in cirrhotic patients investigated whether two antialdosteronic steroids, spironolactone (100-200 mg/day; n = 12 patient pairs) and potassium canrenoate (50-100 mg/day, n = 32 patient pairs) which are reported to bind to intracellular membranes and modify cytochrome P-450, could also produce nuclear changes. The model used was the response of peripheral lymphocytes to blastogenic agents by studying lymphocyte sub-populations. No changes occurred in the B- and T-lymphocyte sub-populations or in the helper and suppressor sub-types. The response to the blastogenic agents, phytohaemagglutinin and purified protein derived from mycobacteria, did not change significantly from before entry into the study to the follow-up (18.1 +/- 2.9 months). All control patients (n = 44 patient pairs) had slightly greater mitogenic activity compared with patients treated with spironolactone; no difference was found when control patients were compared with patients given potassium canrenoate. The difference between spironolactone and potassium canrenoate might be due to toxicity caused by the thio group of spironolactone. Overall, however, both drugs may be regarded as safe, in terms of effects on lymphatic tissue, occurring during the course of cirrhosis.