Fibrin split products were measured by a tanned red cell hemagglutination inhibition immuno-assay in 77 patients with burns and 40 normal individuals who were the controls. The severely burned patient showed only a modest elevation of fibrin degradation products. These results did not correlate well with traditional coagulation measurements which may be affected by a number of mechanisms. The level of fibrin split products did not correlate with the percentage of surface body burns, nor was it of predictive value.