Background: Hospital pharmacy services are one of the hospital's revenue centers and an inseparable part of the hospital's health care system that is oriented towards patient services, quality drug supply, including affordable clinical pharmacy services for all levels of society. The most common problem faced by PKU Muhammadiyah Yogyakarta Pharmacy Installation is the frequent occurrence of vacancies due to uncertainty of drug availability from suppliers, especially FORNAS drugs and vital drugs, which have the potential loss due to having to replace drugs to more expensive ones, and can affect service. Method: This research is a qualitative study with a case study design at the Pharmacy Installation at PKU Muhammadiyah Yogyakarta. Primary data consists of focus group discussions, data on drug use, drug names, and prices of drugs used in PKU Muhammadiyah Yogyakarta. Secondary data consists of searching data and documents in the form of SK for emergency medicine, drug formulary, DOEN, and Clinical Service Guide of the top 10 diseases in the hospital used to find out medicines that are critical for patients. Results: After calculating, the Critical Index Value group was 103 items (6.68%) from the total items in the Pharmacy Installation. Furthermore, the Critical Index B Value group was 643 items (41.73%) of the total items in the Pharmacy Installation. And the Critical Index Value group C: 795 items (51.59%) of the total items in the Pharmacy Installation. After seeing the results of the ABC Critical Index analysis that has been done, in the focus group discussion according to the pharmacists at PKU Muhammadiyah Yogyakarta Hospital ABC Critical Index analysis can be applied in the drug planning process and can be one solution to the problems faced by the Pharmacy Installation PKU Muhammadiyah Hospital Yogyakarta so far Conclusion: The Critical Index ABC method can help PKU Muhammadiyah Yogyakarta Hospital plan the use of drugs by considering the use value, investment value, and criticality value of the drug and can then be used as a xiii basis in determining the formulary policy of the drug that will be the doctor's reference in therapy. Keywords: ABC Critical Index, Pharmacy Installation, Hospital Management