The influence of external sequential compression devices (SCD) on the development of postoperative thromboembolic events was studied in 1,300 consecutive men undergoing radical retropubic prostatectomy. Of the 784 men whose perioperative management did not involve the SCD, in 9 (1.1 %) thromboembolic complications developed: 7 (0.9%) pulmonary emboli (PE), and 2 (0.3%) deep venous thrombosis (DVT). In the 516 patients with SCD prophylaxis there were 12 (2.3%) thromboembolic complications: 9 (1.7%) PE, and 3 (0.6%) DVT In patients with SCD prophylaxis, the delay from the time of surgery to the onset of thromboembolic symptoms averaged 20 ± 12 days, and all but 1 patient suffered the complication while an outpatient; this was significantly longer than in men without SCD (11 ± 5 days; p < 0.05). This delay in thromboembolic events was the only benefit we could demonstrate with SCD. Recognizing that most thromboembolic complications occur after discharge, new strategies for prophylaxis may be needed during this period, and patients should be well informed about the signs and symptoms of PE and DVT to avoid a delay in diagnosis and treatment.