Background: One of the problems that often occurs in mental patients is aggressive behavior. This behavior requires immediate treatment because it can endanger the patient, others, and the environment. Nurses often get attacks from patients in the form of clawed, pulled clothes, spit or other forms of attack. Recent incidents Nurses who were dislocated and beaten by patients. There are no studies on the prevalence of aggressive behavior of patients at Grhasia Mental Hospital. Purpose: To determine nurses' perceptions of the prevalence of aggressive behavior of patients at Grhasia Mental Hospital. Method: This type of research used in this study is a mixed method research that is Sequential Explanatory. Quantitative method is done by using a survey approach that is by distributing questionnaires that will describe nurses' perceptions of the prevalence of aggressive behavior carried out by patients. The instrument used questionnaire Perception of the Prevalence of Aggression Scale (POPAS), Attitude Toward Agression Scale (TOP), and Peceptions of the Prevalence of Aggression Scale. The qualitative method is done by using in-depth interviews with nurses. Results: There is a positive influence between perceptions on aggressive behavior of patients that endanger nurses. This positive value can be seen from the significance which indicates the number 0,000 and the Pearson Spearman rank value 0.922 **. Conclusion: The perception of nurses in Mental Hospital X is in the positive realm with a percentage of 63.7%. The prevalence of aggressive behavior of patients who endanger nurses is mostly in the category of ever, but with a level of behavior that can still be overcome. The tendency of aggressive behavior is in the form of physical threats with a percentage of 92.2%.