Thanks to the discoveries of psychoneuroendocrinoimmunology, we now know that every psychological state is mediated by a specific neurochemical condition and every neurochemical change in turn influences psychological status. We can now identify three different levels of neurochemical mediation of the psychological states: neurotransmission, neuromodulation, and the psychoneuromodulation. Neurotransmission is composed of five main neural pathways, noradrenaline, acetylcholine, dopamine, serotonin, and histamine; neuromodulation; and the psychoneuromodulation. We have performed several clinical studies in an attempt to correlate the psychological status of cancer patients with the immune alterations characteristic of the clinical history of neoplastic disease. We have studied the immunologic status by evaluating cytokine blood levels and the lymphocyte subpopulation; the psychological status was assessed by the Rorschach's test; and spiritual status was evaluated by a previously published test to explore spiritual faith. These preliminary psychological studies seem to suggest that a pre-treatment analysis of psychological and spiritual status may predict the efficacy of both chemotherapy and immunotherapy in advanced cancer patients.