Based on Polish and foreign literature the up-to-date knowledge on usefulness of measurement of the level of acute phase proteins in clinical diagnostics is presented. Acute phase proteins may serve as a quick, preliminary test which indicates bacterial infection or necrotic process. They are good markers of treatment efficacy and infectious (bacterial) complications in patients in a hopeless state or with a chronic disease. In neurological diagnostics they are useful in differentiation of bacterial and viral meningitis.