The concepts of death and authenticity have been two great bastions of the existential phenomenological tradition in psychotherapy, from which the professional work of those who opt for this broad, diffuse and sometimes unknown psychotherapeutic school has been epistemologically based; Several authors have theorised and worked around these concepts, and have highlighted their importance within a process of treatment and transformation of the psyche, giving them a leading role in mental health, sometimes perhaps without a thorough review of what they imply at an ontological level. The main objective of the following paper is the theoretical elaboration of a way of approaching the themes of death and authenticity from existential psychotherapy, starting from the ontological, psychic and anthropological conditions of the human being, as well as from an indication of theology, having as a result the theoretical construction of a resolution as a way of self-care from the existential approach in psychotherapy, offering a general outline to all those who are interested in this approach.