Residential psychiatric patients with severe persistent mental illness are often confronted with unbearable existential suffering. This qualitative study aims to describe how psychiatric nurses in Flanders (Belgium) deal with these patients. In view of the data we describe the nursing support for the existential suffering of these patients in terms of a process-related development. In this process of care four phases can be distinguished: meeting and knowing the patient, acknowledging the patient as an individual and as a sufferer, building a personal caring relationship based on a bond of trust and on respect for the patient as person, and a concluding phase. The personal caring relationship between nurse and patient is the fundamental element in the care practices. Next we describe the contextual framework inasmuch it can influence the caring process in a restricting or stimulating way.