Abstract A review of the literature in the field of psychoneuroimmunology was reported by Robert Ader . Basically, three research approaches have been used to demonstrate a relationship between central sites within the brain that have modulatory influences on the immune system. These include: (1) both the electrical stimulation and surgical lesioning of nuclei in the hypothalamus; (2) traditional behavioral conditioning; and (3) behavioral stress studies. The mechanisms of action for the psychoneuroimmunologic response appear to be focused in three areas: (1) the autonomic nervous system, where direct anatomical connections from the brain to the immune system have been recently demonstrated; (2) the endocrine system where the individual hormones have direct and indirect effects on the immune system; and (3) enkephalins-endorphins in the brain, pituitary, and adrenals that also have direct and indirect effects on the immune system. Examples of drug effects on the above complex systems will be centered on morphine and the enkephalins-endorphins with reference to drugs of abuse, food additives, and cosmetics.