Objective: To study the prevalence and clinical usefulness of antiphospholipid antibodies in different preeclampsia subsets. Design: Observational cross-sectional study. Setting: Tertiary teaching hospital. Patients: Ninety-nine women with preeclampsia versus 83 healthy pregnant women as controls. Interventions: We analysed anticardiolipin IgG/IgM, anti-ß₂glycoprotein IgG/IgM, antiphosphatidylserine IgG/IgM, antiAnnexin-A5 IgG/IgM, and lupus anticoagulant. Main outcome measure: Comparison of antiphospholipid antibody positivity between groups. Results: Antiphospholipid antibody prevalence was 14.14% in the study group vs. 7.23% in controls. Excluding antiAnnexin-A5-positive women, overall antiphospholipid prevalence was 13.19% vs. 3.61% ( p = 0.034). Only IgM-anticardiolipin positivity showed significant differences between preeclampsia group and controls (8.1% vs. 1.20%, p = 0.041). Comparing a severe preeclampsia subset vs. controls, we obtained these significant results: for two or more positive antiphospholipid tests: 9.09% vs. 1.20 ( p = 0.037); IgM-anticardiolipin 10.91% vs. 1.20% ( p = 0.016); IgG/IgM-anti-ß₂glycoprotein-I 10.91% vs. 1.90% ( p = 0.016), IgM-anti-ß₂glycoprotein-I 9.09% vs.1.20 ( p = 0.037). When comparing early-onset preeclampsia vs. controls we found IgM-anticardiolipin 11.11% vs. 1.20% ( p = 0.029). Conclusions: Prevalence of antiphospholipid antibodies in preeclampsia patients is twice that in healthy pregnant women. Multipositive aPL test, IgM-anticardiolipin and IgM-anti-ß₂glycoprotein-I isotypes showed an association with severe and early-onset preeclampsia. Larger studies are needed to establish the usefulness of antiphospholipid tests as risk markers for severe and early onset preeclampsia.