SummaryThe main techniques for detection and quantitation of fibrinopeptide A and fibrin monomers, and the application of these techniques to the diagnosis of low grade or local activation of intravascular coagulation, are briefly reviewed. Radioimmunoassay of FPA provides direct, sensitive and specific quantitation of thrombin activity; elevated levels of FPA have been found in numerous clinical situations in which there is intravascular activation of the clotting system. Among the various tests for the detection and quantitation of fibrin monomers, agarose gel chromatography and affinity chromatography on insolubilized fibrinogen appear to be the most useful for the diagnosis of low grade or local intravascular coagulation in several diseases. All these tests, however, are not yet rapid or simple enough to be applicable to routine clinical testing.