It was to be investigated whether the elimination rate of 14-hydroxy-3beta-[(4-O-methyl-alpha-L-rhamnopyranosyl)oxy]-14beta-bufa-4,20,22-trienolide (meproscillarin, Clift) is influenced by the renal function after discontinuance of long-term application. A group of 9 patients with renal insufficiency of varying extent associated with heart failure received 0.75 mg of meproscillarin per day over a period of 14 days. The plasma levels of the glycoside were measured by means of the 86rubidium erythrocyte assay up to 60 h after the last dose. After discontinuance of the glycoside the mean plasma half-life was 45.8 (S.-X = 6 h), a value corresponding to the results obtained in healthy test persons (49.3 h). Thus it could be demonstrated that the rapid elimination rate (and thereby the rate of inactivation) of meproscillarin is not influenced by renal function even after discontinuance of long-term application.