Soluble fibrin (SF) and D-dimer are useful for making the diagnosis of deep vein thrombosis (DVT). However, the evidence for using such markers and optimal timing to diagnose postoperative DVT are unclear. We evaluate the usefulness of SF and D-dimer testing for the diagnosis of postoperative DVT. A total of 207 patients who had total hip arthroplasty or knee arthroplasty were evaluated. SF and D-dimer were tested on postoperative days 1 and 7. DVT was confirmed with ultrasonography. SF level on postoperative day 1 was the most useful, although D-dimer evaluation on postoperative days 1 and 7 was also useful. Using a SF cut-off of more than 4.00 microg ml(-1), the sensitivity was 90%, the specificity was 33%. Although the SF and D-dimer tests cannot be used as stand-alone tests, SF and D-dimer are valuable screening tools. We recommend two-stage screening including first with the SF or D-dimer test, followed by ultrasonography or venography.