To assess test characteristics of the uterine artery score (UAS) and mean pulsatility index (PI) in prediction of poor obstetric outcome in high-risk pregnancies. Blood flow in the uterine arteries between 21 and 28 gestational weeks were studied in 157 high-risk women. The uterine artery score (UAS), as described by Hernandez-Andrade et al. (UOG 2002;19 : 438-42), was analysed in two ways; normal flow (UAS 0) vs. a positive score (UAS = 1 + 2 + 3 + 4) or low score (UAS = 0 + 1 + 2) vs. high score (UAS = 3 + 4). The mean uterine artery PI was divided into low mean PI (< 1.2) or high mean PI (> 1.2). Since high mean PI (> 1.2) and high UAS (3 + 4) occured in the same women, except for one, the analysis was restricted to a comparison between negative vs. positive UAS and low vs. high mean PI. Poor obstetric outcome was defined as preeclampsia or hypertension resulting in preterm delivery (< 37 weeks) or IUGR below the 3rd centile or placental abruption occuring at any gestational age. 56 (37%) women had preterm delivery (< 37 weeks) and 21 of them delivered because of preeclampsia or severe hypertension. There were no intrauterine fetal deaths, 2 cases of placental abruption and 3 children had isolated IUGR. In all, 42 (27%) women had cesarean section, and 23 (15%) of newborns were transferred to NICU. Positive UAS had sensitivity (DR) 76%, false positive rate (FPR) 32%, positive predictive value (PPV) 27% and likelihood ratio (LR) 2.4 for poor obstetric outcome. High mean PI had DR 48%, FPR 5%, PPV 59% and LR 9.3 for poor obstetric outcome. If poor obstetric outcome was restricted to preeclamptic pregnancies delivered < 34 weeks (9 of 152 women), mean PI had DR 78%, FPR 6%, PPV 44% and LR 12.3. Mean uterine artery PI is a reasonably good predictor for poor obstetric outcome. Notches in the velocity waveform do not seem to add much to the prediction of disease. Test characteristics are dependent on the study population and the definition of poor outcome.