ABSTRACT.Urinary excretion of prostaglandin E2(PGE2) and F2a (PGF2α), plasma concentrations of renin (PRC), aldosterone (PAC), noradrenaline (PNA) and adrenaline (PA) were determined in the third trimester of pregnancy, 5 days and 3 months after delivery in preeclampsia and normotensive pregnant and non‐pregnant control subjects. PGE2was higher in pregnant control subjects than in non‐pregnant subjects, but reduced to non‐pregnant level in preeclampsia. PGF2a was the same in preeclampsia and normotensive pregnancy but higher than in the non‐pregnant group. PRC and PAC were increased during pregnancy, but considerably lesser in preeclampsia than during normotensive pregnancy. PNA and PA were the same in all three groups. All parameters were normal 3 months after delivery. There were no correlations between any of the hormones and blood pressure in any of the groups. PGE2was positively correlated to PRC. The lack of renal PGE2in preeclampsia might be responsible for the decrease in renal blood flow and sodium excretion, and the changes in PRC and PAC are supposed to be secondary to changes in PGE2. It is hypothesised that preeclampsia is a state of prostaglandin de