The consequences at the cardiac level of adriamycin treatment alone or in association with the cardiac glycoside beta-methyldigoxin, were evaluated with reference to the PEP/LVET ratio, heart rate, and minimum blood pressure. The variation usually seen in the PEP/LVET ratio when adriamycin is administered alone was not observed when pretreatment with beta-methyldigoxin was also given. A similar situation is found with variations in blood pressure and heart rate. From a pharmacokinetic point of view, this treatment scheme does not seem to affect the general behavior of the antibiotic.