From the pre-natal follow-up it was remarkable that cases have been admitted relatively late. Hints to a possible development of preeclampsia could be seen from patients history or the routine check up, for example the registration of edema, fetal growth retardation and oligohydramnios. For early diagnosis of preeclampsia we recommend: Calculation of mean arterial blood pressure or its non-invasive measurement; determination of hematocrit, uric acid and total plasma protein (in particular hemorheologic measurements). Hypomagnesemia in preeclampsia, as described by some authors, was also seen in our cases. The complex symptomatology of preeclampsia could be attributed to a generalised disturbance of microcirculation, which leads to definite reactions of the organs concerned. The microcirculatory failure is caused by vasoconstriction, hemoconcentration, hyperviscosity and hypercoagulation (up to DIC and consumption coagulopathy). The resulting symptoms and syndromes can be: EPH, HELLP, hemolytic-uremic Syndrome, hepato-renal Syndrome, thrombocyte and antithrombin III deficiency etc. The drug of choice for treatment of preeclampsia is magnesium sulfate. Its application is based on long-term clinical experience and new aspects on the physiologic and pharmacologic role of magnesium. The recommendations of the German High Blood Pressure League to use calcium antagonists as a basis in the treatment of high blood pressure can be fulfilled particularly in pregnancy by the physiologic calcium antagonist Mg++. Magnesium sulfate should be given in a dosage of 24-72 g daily. The dose should also be made dependent from urinary output. Further treatment patterns of preeclampsia should be adjusted according to each case. The present results also support our hypothesis that magnesium deficiency (besides predisposing factors) could be responsible for the development of preeclampsia (present model shown in detail). Consequently, the early and long-term substitution of magnesium in pregnancy could help reduce preeclampsia.