In recent decades, the elderly population in Brazil has grown rapidly, as has concern for the health of this population. Institutionalization in nursing homes has appeared as an alternative form of health care for frail elderly that live alone. The present study evaluated the pharmacotherapy and inappropriate drug prescriptions for institutionalized elderly patients living in long-term institutions in southeastern Brazil. This research was conducted at five institutions with a total sample of 151 individuals aged at least 60 years. Databases were used to identify drug interactions, defined daily dose and inappropriate prescriptions. The prevalence of drug intake among the elderly was 95.36%, and there were an average of 3.31 ± 1.80 drug prescriptions per individual. Based on Beers criteria, the prevalence of inappropriate prescriptions was 25.83%. In addition, 70.2% of prescriptions were prescribed at a higher dosage than the defined daily dose (ATC/WHO). Potential drug interactions were identified for 54.11% of prescriptions; 81.42% of these were of moderate severity. The main inappropriate drugs were prescribed for cardiovascular and nervous system problems. Institutionalized elderly individuals presented a high consumption and misuse of medications, requiring professional intervention to monitor prescriptions and improve the quality of service for this population.