Pregnancy-induced hypertension and preeclampsia account for about 25% of perinatal morbidity and mortality and are a leading cause of maternal death in developed countries. Consequently, early diagnosis of the disease seems very important. Numerous clinical and biochemical methods have been described and tested for the prediction of preeclampsia. The results of these studies are critically described here. In summary, no test presently available serve as a reliable early marker of developing preeclampsia. However, vaginal Dopplerultrasound may allow prediction as early as the 12th to 16th week of gestation. Moreover, methods detecting underlying mechanisms of the disease such as endothelial dysfunction and platelet activation, are being developed and might provide improved early identification of pregnant women at high risk.