In the diagnostic management of patients with clinically suspected recurrent deep-vein thrombosis (DVT), there are potential limitations to all available diagnostic techniques. Since venous abnormalities may persist for some time after an acute thrombosis, the usefulness of compression ultrasonography (US) for the detection of recurrent DVT may be jeopardized. We determined the rate of normalization of an abnormal compression US test of the popliteal and the common femoral veins in patients after a first episode of proximal DVT. In a cohort of 60 consecutive patients, the test result was normalized in only 29, 44, 54, and 60% of patients at 3, 6, 9, and 12 months, respectively. The investigation shows that for the detection of recurrent DVT of the leg, real-time compression US (using the single criterion of compression of the common femoral and popliteal vein) is of limited value. Future studies need to be performed, using more subtle interpretation of the compression US result, by quantifying the extent of residual thrombus, which may increase the usefulness of this test in patients with recurrent symptoms.