This study illuminates how existential needs and spiritual needs are connected with health care ethics and individuals' mental health and well-being. The term existential needs is defined as the necessity of experiencing life as meaningful, whereas the term spiritual needs is defined as the need of deliverance from despair, guilt and/or sin, and of pastoral care. It discusses whether or not patients' needs are holistically addressed in Western health care systems that neglect patients' existential and spiritual needs, because of their biomedical view of Man which recognizes only patients' physical needs. It excludes a holistic health care which considers all needs, expressed by patients in treatment of mental illness. Addressing all needs is important for patients' improvement and recovery. For some patients, this is the only way to regain their mental health and well-being.