Inflammation is a complex and necessary component of an organism's response to biological, chemical or physical stimuli. In the acute phase, cells of the immune system migrate to the site of injury in a carefully orchestrated sequence of events that is mediated by cytokines and acute phase proteins. Depending upon the degree of injury, this acute phase may be sufficient to resolve the damage and initiate healing. Persistent inflammation as a result of prolonged exposure to stimulus or an inappropriate reaction to self molecules can lead to the chronic phase, in which tissue damage and fibrosis can occur. Chronic inflammation is reported to contribute to numerous diseases including allergy, arthritis, asthma, atherosclerosis, autoimmune diseases, diabetes, and cancer, and to conditions of aging. Hematology and clinical chemistry data from standard toxicology studies can provide an initial indication of the presence and sometimes location of inflammation in the absence of specific data on the immune tissues. These data may suggest more specific immune function assays are necessary to determine the existence or mechanism(s) of -immunomodulation. Although changes in hematology dynamics, acute phase proteins, complement factors and cytokines are common to virtually all inflammatory conditions and can be measured by a variety of techniques, individual biomarkers have yet to be strongly associated with specific pathologic events. The specific profile in a given inflammatory condition is dependent upon species, mechanisms, severity, chronicity, and capacity of the immune system to respond and adapt.