Patients with disseminated intravascular coagulation (DIC) exhibit increased levels of fibrin/fibrinogen degradation products (FDP), and FDP levels are carefully monitored as a marker of fibrinolysis during the diagnosis of DIC and other fibrinolysis-related conditions. Although FDP levels can be measured using automatic analyzers, it is reported that measured FDP values differ depending on the reagent used. Recently, a newly developed reagent for measuring FDP levels (Lias Auto P-FDP) was launched. In this study, we used Lias Auto P-FDP in combination with the Coapresta 2000 automatic analyzer and evaluated its reactivity. We confirmed the reproducibility of the measurements obtained with the Lias Auto P-FDP reagent when the manufacturer's instructions were followed and that the Lias Auto P-FDP reagent can be used with the Coapresta 2000. In the reactivity test, the Lias Auto P-FDP reagent exhibited stronger reactivity with low molecular weight FDP than the reagent we currently use (BL2 P-FDP). Moreover, the samples that exhibited non-specific reactions to the BL2 P-FDP reagent did not display similar reactions to the Lias auto P-FDP reagent. In the clinico-pathological analysis of divergent value between Lias Auto P-FDP and BL2 P-FDP, seven cases were highly discrepant value of FDP. Interestingly, we found the description of pleural fluid and/or ascites in 85.7% cases. In conclusion, we confirmed that the Lias Auto P-FDP reagent can be used in combination with the Coapresta 2000. In addition, the reactivity of FDP varied depending on the reagent used. It is important to understand the characteristics of each FDP reagent and which automatic analyzers they can be used with. [Original].