Background/Objectives: An association between biomarkers of trans fat intake and greater risk of preeclampsia has been reported, but research in this area is scant. Thus, we examined the association of second trimester intake of trans fats with risk of preeclampsia and severe preeclampsia. Subjects/Methods: We followed 67 186 pregnancies of women participating in the Danish National Birth Cohort between 1998 and 2003. Diet was assessed with a food frequency questionnaire at gestation week 25, and preeclampsia diagnosis was obtained by linkage with the Danish National Patient Registry. Results: There were 1804 cases of preeclampsia and 402 cases of severe preeclampsia identified in the cohort. Intake of trans fats decreased during the study period as a consequence of a reduction in industrial trans fat intake. Second trimester intake of trans fats was unrelated to risk of preeclampsia or severe preeclampsia. The relative risk (95% confidence interval; P, trend) of preeclampsia and severe preeclampsia comparing top to bottom quintiles of trans fat intake were 0.95(0.81; 1.11, 0.33) and 1.07 (0.78; 1.48, 0.92), respectively.Conclusion:Second trimester intake of trans fats is unrelated to risk of preeclampsia within the intake range observed in a period of gradual reduction of industrial trans fats from the Danish food supply.