A 3-year retrospective study (1992 to 1995) was done to identify all cases of Greenfield filter use in pregnant patients cared for by the Maternal-Fetal Medicine Service of our institution. The patient selection criteria included placement of a Greenfield filter in the index pregnancy or placement of a Greenfield filter before conception and in a patient who subsequently became pregnant. A series of eight pregnant patients with Greenfield filters was identified, the largest to date in a single institution. Management of the pregnant patient at risk for pulmonary embolism or its recurrence is problematic. Hypercoagulability occurs during pregnancy and predisposes the at-risk patient to thromboembolic phenomena such as deep venous thrombosis and pulmonary embolism. This study, though limited, indicates that Greenfield filters may be used safely in pregnant women and are effective in preventing pulmonary embolism or its recurrence.