Background: Although polypharmacy may be justified in elderly patients with multiple diseases, it may be dangerous, especially when it includes potentially inappropriate medications (PIM OR=15.0, OR=5.0; respectively). Thirty one percent of participants using non-steroidal anti-inflammatory drugs, were not receiving medications for gastric protection. One to four drugs included in the Beers list were prescribed to 66% of participants. Conclusions: Despite the high prevalence of use of antacids and anti-ulcer agents, these drugs were not prescribed to a significant proportion of patients using non-steroidal anti-inflammatory drugs. Strategies to optimize pharmacotherapy in the elderly population are urgently required. (Rev Med Chile 2013; 141: 194-201).