Plasma from pregnant women with preeclampsia was screened for the D-dimer, a degradation product specific for crosslinked fibrin, using a monoclonal antibody (DD-3B6), latex-bead agglutination assay (DIMERTEST). Seventy-nine of 204 (38.7%) of the preeclamptic women and none of 88 healthy non-preeclamptic women were positive for the D-dimer. Presence of the D-dimer correlated consistently with elevated fibrin(ogen) degradation products, detectable fibrin monomer, and platelet count less than or equal to 100 X 109/L, with a 93.0% sensitivity overall for abnormalities of the same. Among D-dimer-positive women, 66.7% had fibrin(ogen) degradation products less than 10 µg/mL, 60.3% had no detectable fibrin monomer, and 82.0% had platelets greater than 100 X 109/L. When compared with D-dimer-negative preeclamptic women, D-dimer-positive women had significantly higher blood pressures prompting delivery, greater proteinuria, more abnormal liver function tests, and higher serum creatinine and blood urea nitrogen. In addition, they had a greater risk of cesarean section (49.4 versus 34.4%), premature delivery (58.2 versus 20.0%), low birth weight (54.5 versus 20.3%), low Apgar scores, and an abnormally high ratio of female to male offspring (1.72 versus 0.93). Testing for the fibrin D-dimer may be useful in early screening and follow-up for preeclamptic coagulopathy, and may also help to define the subset of patients with severe disease.