Quantitative modifications of beta-naphthol, ethanol, and protamine sulfate tests are described, which are based on spectrophotometry of the formed precipitate. The findings have demonstrated a correlation between these tests' results and the plasma fibrinogen concentration. It is recommended that the paracoagulation test parameters be estimated with consideration for fibrinogen level. The results of measurements of the plasma fibrin monomer soluble complexes in 13 donors and in 72 patients with blood diseases and hemostasis are presented. The results permit a conclusion that these tests used alone or in various combinations are sufficiently sensitive, specific, and informative for the examinations of patients with disseminated intravascular coagulation; combined use of three paracoagulation tests has been found to be optimal.