Patient [[safety]] indicators (PSI) are a set of potentially preventable events related to patient safety and opportunities for improvement. Eight pertinent PSI have been identified in patients with [[aneurysmal subarachnoid hemorrhage]] (ASAH), such as [[decubitus ulcer]], and central line-related bacteraemia. The aim was to evaluate the [[efficacy]] of a [[health care]] [[quality protocol]] to prevent the appearance of PSI in ASAH patients. Methods: Adult patients treated for ASAH were included in a retrospective control group of 35 patients and a prospective experimental group of 35 patients when the prevention program was implemented. We evaluated the occurrence of PSI, and its relation to age, sex, Hunt and Hess scale grade, type of aneurysm treatment, length of hospital stay, and Glasgow Outcome Scale scores. Results: Both groups had similar characteristics except for a longer hospital stay in the control group. The overall PSI prevalence decreased significantly in the experimental group compared to the control group. The experimental group had a decreased risk for having at least one PSI: OR = 0.21 (0.08-0.57, CI 95%). The absolute risk reduction is 37.1% (58.9%-15.4%), the preventable fraction for the population is 28.3% (10.6%-40.0%), and the number needed to treat is 2.69. Conclusions: The health care quality protocol is effective to prevent ISP in ASAH patients. Implementing this prevention program has no effect on the neurological state of the patient at the hospital discharge. Still, it is successful in decreasing the PSI prevalence and the days of hospital stay ((Revilla-Pacheco F, Calderón-Juárez M, Lerma A, Herrada-Pineda T, Lerma C. Efficacy of an intervention program to prevent patient safety indicators in aneurysmal subarachnoid haemorrhage. Br J Neurosurg. 2021 Jun 7:1-6. doi: 10.1080/02688697.2021.1931810. Epub ahead of print. PMID: 34096815.)).