Preeclampsia, intrauterine growth retardation, and abruptio placentae are associated with the failure of the placenta to create an adequate communication with the maternal vasculature and subsequently reduced placental perfusion, with secondary effects on villous maturation and placental function, thereby failing to meet the needs of the growing fetus. Also, primary failure of placental maturation has been linked with the chromosomally abnormal fetus. Doppler ultrasound allows examination of blood flow in maternal and fetal vessels and assists in our ability to understand, predict, and diagnose pregnancy complications. Over the last 10 years there has been a rapid development in the capacity and complexity of the equipment used for clinical Doppler examination, from simple continuous wave devices to duplex-color flow systems, and the advantages of these developments continue to be defined. As with all innovations there has been a period of extensive appraisal of this technology, and further applications of Doppler await clarification. This review puts the most recent publications in perspective, and points to the likely areas of interest in the future.