The elderly represent the fastest growing age group in Brazil, making their demand for health resources more intense, both in terms of the use of services and the use of medicines. Due to the prevalence of chronic degenerative diseases and various other comorbidities, polypharmacy has become a frequent practice and a major problem in the health care of the elderly. The aim of this study is to describe and compare the prevalence of polypharmacy and the use of inappropriate medication in institutionalised elderly people and elderly people receiving outpatient care, helping to expand the knowledge of health professionals and academics about the profile of medication use in the elderly and providing data that should help in the management and prevention of polypharmacy and its consequences for the health of the elderly.