INTRODUCTION Patients with a psychiatric disorder (PPD) are eligible to request physician assisted death (PAD) in a small but growing number of jurisdictions, including the Netherlands and Belgium. In Canada, after March 2023, people with a mental illness as their sole underlying medical condition will have access to PAD. For this request to be granted, most of these jurisdictions demand that the patient is competent in her request, and that the suffering experienced is unbearable and irremediable. (Kim, de Vries and Peteet, 2016; Shaffer, Cook and Connolly, 2016) The criterion of irremediability is particularly difficult to establish in psychiatric disorders. (van Veen, Ruissen and Widdershoven, 2020) Retrospective casefile studies of Dutch PPD who died through PAD show if experts disagree on a criterion, it often concerns irremediability. (Kim, de Vries and Peteet, 2016; van Veen et al., 2018) A Dutch euthanasia expertise center recently stated that more clarity on psychiatric irremediability is a priority. (Kammeraat and Kölling, 2020) A Canadian expert advisory group has also called for more research on the irremediability of psychiatric suffering. (Gaind, 2020) A recent qualitative study on irremediable psychiatric suffering (IPS) among Dutch psychiatrists with experience in establishing IPS in the context of PAD concluded that consensus-criteria are needed to guide current clinical decision-making. (van Veen et al., 2020) Moreover, jurisdictions debating PAD for PPD in the future may benefit from the availability of essential criteria for establishing IPS, developed from the relatively longer practice experiences in the Netherlands and Belgium. If jurisdictions choose to allow PAD for PPD, minimum essential criteria for IPS should also be specified when drafting legislation. Finally, researchers can use criteria of IPS for designing clinical studies on the irremediability of therapy resistant psychiatric disorders and their management. In this study, we use a Delphi-method to develop expert consensus-criteria for IPS in the context of PAD, focusing on the Netherlands and Belgium where PAD has been permitted in psychiatric practice for over 20 years. Therefore, we address the following research question: what are the criteria that Dutch and Belgian experts agree upon for IPS in the context of PAD for PPD? A DELPHI STUDY ON IRREMEDIABILITY | 99 6