Nurses who attend patients with psychiatric disorders often encounter ethical dilemmas and experience difficulties in making the right decision. The present study aimed to evaluate the decisions of psychiatric nurses regarding their duty to warn third parties about the dangerousness of the patient, the need for compulsory hospitalization, and the competence of patients. In total, 111 nurses working in the field of psychiatry in Turkey completed a questionnaire form consisting of 33 questions. The nurses generally assessed the decision-making competency of the patient correctly. However, their decisions regarding whether the patient should be compulsorily hospitalized and their understanding of their duty to warn/protect were less consistent. A significant relationship was found between the decisions of the psychiatric nurses and their work experience, them having children, and them having postgraduate education in psychiatric nursing. The nurses stated their desire to be part of the team that decided on ethical problems in psychiatry.