Pro re nata (PRN) medication is widely used and studied in psychiatric care, but our knowledge about patient participation in its admini stration is fragmented . The aim of this integrative review was to describe and synthesize previous knowledge of patien t participation in PRN in psychiatric inpatient settings. We conduct ed both electronic and manual searches, using the CINAHL, Scopus, PsycINFO, and PubMed databases, and eight scientific journals. Searches were limited to the English language, to the years 2006 – 2016, and to selected papers using inclusion, exclusion, and quality criteria. We identified 16 relevant papers, and these showed that patient participation included patient-related starting points, including the patients’ willingness to participate and their knowledge of the medication. The patien ts’ participation in PRN practices was demonstrated by the oppo rtunity to request PRN and to refuse any PRN that was offered. Patient participation was shown to be linked to certain situa tions where PRN was recommended. The role that the profession als played in patient participation included interacting with patients, providing counselling and alternatives for PRN. Our results also revealed that coercion was used administering PRN. The existing literature exposed challenges that need to be addressed if patient participation in the use of PRN medication is to be effectively achieved in psychiatric inpatient settings. Equal partnerships between patients, nurses, and physicians are an essential part of this process, and further research into PRN medi cation is urgently needed, particularly studies that focus on patients’ experiences.