Compared to well documented studies on immunosuppression "psychologically induced immunoenhancement" is a rather neglected topic in medical literature and research, even in the new established field of psychoneuroimmunology. Starting with the premise that research questions emanating from this field and from behavioural medicine may provide critical information for understanding the phenomena of immunomodulation, evidence and illustrations of psychologically induced immunoenhancement are provided in the context of psychosocial neuroimmunomodulation. Distress-reducing interventions such as progressive relaxation training, imagery, experimentally induced short-term positive mood states and mirthful laughter enhances various aspects of immune functions, i.e., primarily the phylogenetically old paraspecific parameters. Additionally, a larger variety of emotional/psychosocial factors with potentially but yet unproved immunoenhancing effects seems to exist. In particular, enhancement of phagocytosis, NK cell and T cell response to phytohemagglutinin, decrease in the number of suppressor/cytotoxic T cells and increase in the number of circulating T helper/inducer cells in peripheral blood, and enhancement of spontaneous lymphocyte blastogenesis as well as cytokines have all been shown to be associated with the above mentioned intervention techniques.