We investigated the effects of specimen storage conditions on the analysis of the coagulation molecular markers, soluble fibrin (SF), thrombin-antithrombin complex (TAT), thrombomodulin (TM) and tissue plasminogen activator inhibitor-1 complex (total PAI-1: tPAI). Marker levels were measured using a STACIA automatic coagulation analyzer. Among these four markers in blood from healthy subjects, only tPAI increased gradually with time, and the differences were especially marked when blood samples were stored at room temperature. Patient blood samples were stored for 4 hours under three different conditions: whole blood storage on ice, storage on ice after centrifugation, and refrigerated storage after centrifugation. Analytical results were compared between the three sets of samples. There were no significant differences in TAT or TM after 4 hours' storage under the different conditions. However, SF was decreased in several samples. In 11 of 14 samples with >20 microg/ml SF, SF levels were reduced by >10 microg/ml when whole blood without centrifugation was stored on ice. tPAI levels increased slightly after storage for 4 hours under all three conditions. These results suggest that centrifugation followed by refrigeration is the optimal storage method for blood samples when all four markers are to be measured simultaneously in the same sample.