Twenty-two hospitalized patients, diagnosed as having hypertensive disorder of pregnancy, were selected from two University Clinics. Maternal serum samples were analyzed for serum group II phospholipase A2 (PLA2-II) by time-resolved fluoroimmunoassay. At the same time, umbilical artery blood flow velocities were measured with color Doppler sonography for orientation and pulsatile Doppler sonography for recording waveforms. Nineteen normoten-sive third-trimester pregnant patients served as a control group. Maternal serum PLA2-II was elevated in 8 cases with preeclampsia. This elevation was invariably associated with decreased blood flow velocity in the umbilical artery. In 1 case, the clinical condition allowed simultaneous follow-up of serum enzyme and blood flow velocity: a further rise of serum PLA2-II was linked to a further decrease in the blood flow velocity of the umbilical artery. A large spillover of the elevated PLA2-II content from the preeclamptic placenta into the maternal serum is associated with a decrease in blood flow velocity in the umbilical artery. The enzyme might serve as a link between local proximal (placenta) and systemic distal (umbilical arterial blood flow) effectors.