Drug-related iatrogenesis is an important issue in the elderly population, and preventing iatrogenic accidents helps to reduce hospitalizations. Our study’s objective was to evaluate prescriptions in the geriatric population of our establishment. The study conducted is a targeted clinical audit. Ten criteria were tested on the hospital prescriptions of people over 75 years old in 11 medical departments, before and after improvement actions. The non-compliance threshold was set at 10% of prescriptions for each criterion. In each phase, 165 patients were included. Four criteria were non-compliant (NC) in the first phase: the presence of Potentially Inappropriate Medications for the Elderly (PIMs) (NC = 57.6%), the adaptation of the medication to renal clearance (NC = 24.9%), the presence of illogical combination (NC = 9.7%), and the total anti-cholinergic score of the prescription (NC = 12.1%). After the implementation of improvement actions, the number of non-compliant criteria decreased between the two phases, from four to two. We obtained a significant improvement for three of the four criteria found to be non-compliant in the first phase. The criterion adaptation to renal function is close to compliance (NC = 10.1%) and the PIMs criterion remained non-compliant after reassessment (NC = 32.1%). Vigilance must be ongoing in order to limit drug iatrogeny, particularly in frail elderly patients.