An International Syaposiua on Free Radicals in Diagnostic Medicine was co-sponsored by the state University of New York at Buffalo, Roswell Park Cancer Institute, and the Upstate NY Section of the American Association of Clinical Chemistry. The theme was "A Systems Approach To Laboratory Technology, Clinical Correlations And Antioxidant Therapy." The symposium was held on October 7-8, 1993 at the Hyatt Hotel and on October 9 at Roswell Park Cancer Institute, Buffalo, New York. This proceedings volume contains chapters from platform presentations, poster sessions and from invited special lectures in the areas of basic science, clinical applications and efficacy of treatment. A Special Lecture on the relevance of free radical analysis to clinical medicine was presented by Professor Kunio Yagi of Japan. The Yagi procedure to measure thiobarbituric acid (TBA) reaction reflects the amount of reactive substances, lipid peroxides and aldehydes, in the sample. For example, normal subjects will have less than 4 nmol/ml of serum lipid peroxides, while a person with diabetes generally has equal or greater than 5.0 and a diabetic person with vascular complications often exceeds 7.5 nmol/ml. Serum TBA is a clinically important measure that relates to aging, gender and estrogen as an antioxidant, in the prognosis for vascular disorders, and in pathological conditions relative to the amount of lipid peroxidation. The BASIC SCIENCES portion of the program examined: "Mechanisms of Action, Pathophysiology and Laboratory Tests" in six presentations.