The purpose of our study was to compare performance between Medicare Advantage and stand-alone prescription drug plans on the two quality assurance measures of drug-disease interaction and drug-drug interaction for elderly heart failure beneficiaries. Performance on the drug-disease interaction measure appeared more problematic for stand-alone plan enrollees compared with Medicare Advantage plan enrollees. No statistical difference existed between the plans regarding drug-drug interactions. It appears there may be considerable room for more sophisticated use of disease profiling in the processing of drug claims. The provision of richer clinical data is an essential step to improving performance on the drug-disease interaction measure.