Anesthesia practitioners have begun to focus on the immune function of their patients as more research is done on the interface between anesthesia, surgery, and immune alterations. The anxiety associated with anesthesia and surgery produces alterations in immune function through several mechanisms which affect recovery from surgery and wound healing. Immune status may be assessed by traditional measures such as complete blood count and differential as well as using newer technologies such as flow cytometry, lymphocyte proliferation assays and natural killer cell cytotoxicity. Anxiety produces immune changes through sympathetic adrenal medullary and hypothalamic pituitary adrenal cortical mechanisms, as well as through the neurotransmitter substance P. Anxiety also produces changes in immune function through alteration in health behaviors such as increased smoking, increased alcohol consumption, drug use, and changes in diet and sleep. Recommendations for psychological and pharmacological measures that are effective in reducing stress-induced immunosuppression among this group of patients are provided. The future use of substance P antagonists, which are currently under investigation, as well as cytokine manipulation, hold promise for further measures to reduce immune alterations associated with anxiety.