Objectives: To determine the usage rate of those drugs included in the Beers criteria, and detect treatment patterns susceptible of pharmaceutical intervention by means of alerts related to their computer-assisted prescription. Method: Prospective study where the treatments of patients admitted to the hospital geriatric units were reviewed. A weekly review took place during six consecutive weeks (February; to March 2008). We identified potentially dangerous drugs included in the 2002 Beers list, as well as the prescriptions of two or more benzodiazepines. Results: We reviewed 4,677 pharmacological lines in 584 treatment orders. 2.18% (102/14,677) of the prescriptions were from a drug under analysis. In 8 out of 584 medical orders two similar ha half-life benzodiazepines coexisted. The most prescribed potentially dangerous drugs for the elderly patient were: pethidine (49/102), clorazepate dipotassium (11/102), amiodarone (7/102), doxazosin (6/102) and kerotolac (4/102). Conclusions: The percentage of prescriptions included in the Beers list is lower than that of other national studies. Currently, the pharmacy, department suggests other therapeutic alternatives with electronic prescription when prescribing meperidine, kerotolac, long or intermediate-acting benzodiazepines, or two or more benzodiazepines.