Aim: To evaluate the efficacy of a combined 2nd-trimester maternal serum homocysteine and uterine artery Doppler screening at 20 weeks of gestation for complications of pregnancy: preeclampsia, isolated intrauterine growth restriction (IUGR), placental abruption, and stillbirths. Methods: Consecutive singleton pregnancies without previous risk factors who had homocysteine measured as part of a serum-screening program for trisomy 21 had uterine artery Doppler performed. Sensitivity, specificity, positive and negative predictive values, odds ratio, and positive and negative likelihood ratios for the subsequent development of preeclampsia, isolated IUGR, placental abruption, stillbirth, and preterm delivery were calculated for the following methods (1) homocysteine cutoff level 6.3 mu mol/l (95th centile); (2) on Doppler ultrasound bilateral notches with a mean resistance index (RI) >0.55 (50th centile), all unilateral notches with a mean RI >0.65 (80th centile), and absence of notches with a mean RI >0.7 (95th centile), and (3) Doppler ultrasound notch evaluation (bilateral, unilateral, absence as in method 2) combined with the homocysteine cutof level of 6.3 mu mol/l. Results: By using a logistic regression model, methods 1 and 2 predicted preeclampsia (p < 0.001), isolated IUGR (p < 0.01), and 'any complication' (p < 0.01). The sensitivity for prediction of preeclampsia using the combined method (3) was 61.3% for a false-positive rate of 2%, better than that for isolated IUGR (54%) below the 5th centile and 'any complication'(56%). Conclusion: This prospective study confirms the potential of a combined method of elevated homocysteine and uterine artery Doppler screening for preeclampsia, isolated IUGR, and any obstetric complication. Copyright (C) 2006 S. Karger AG, Basel.