Immobilized streptococcal T1-, T3- and T4-proteins to AH-Sepharose 4B were tested for their ability to absorb human fibrinogen. Purified fibrinogen and plasma samples were used for affinity chromatography. T1-protein was able to retain specifically fibrinogen from plasma. T4-protein bound fibrinogen in a similar manner, but it was not as specific as T1-protein. T3-protein failed to bind purified fibrinogen as well as fibrinogen from plasma. Adsorption of fibrinogen was accomplished using a 0.05 M phosphate/0.2 M NaCl/0.02% NaN3/pH 7.0 buffer system followed by elution with 0.05 M PO4/1 M NaCl/0.02% NaN3 to remove non specifically bound components. Retained components were eluted with 8 M Urea/0.025 M NaOAc, pH 5 and the fractions analyzed for fibrinogen content by SDS polyacrylamide gel electrophoresis. The presence of fibrinogen was determined by observations of the characteristic A alpha, B beta and gamma chain bands.