OBJECTIVE: To aim of our study is to support the correlation between blood pressure and asymmetric dimethyl argine (ADMA) concentrations as a possible marker for early diagnosis of the preeclampsia syndrome.STUDY DESIGN: We attempted to calculate in 38 pregnant women with preeclampsia (group A) plasma levels of the main inhibitor to nitric oxide synthase (NOS), which is ADMA, and to compare our findings with the levels of ADMA in 36 non preeclamptic pregnant women (group C) and also with the levels in 29 pregnant women who had a history of preeclampsia in previous pregnancies (group B). Maternal venous EDTA plasma samples of 5 ml were collected and analyzed to measure the ADMA concentrations in each subject. Statistical analysis was performed using the Graph Pad Instat Mann-Whitney test, unpaired, non parametric test, two-tail p values.RESULTS: There was no statistical difference between the three groups regarding maternal and gestational age (24-32 weeks). There was a significant statistical difference between the three groups regarding ADMA levels. The two-tailed p value between group A and group C (normal group) was < 0.001, between group A and group B < 0.002 and between group B and group C < 0.002.CONCLUSION: In conclusion we have observed that ADMA probably fulfills many of the criteria to be characterized as a preeclamptic factor and an accurate cut-off point matched to each week of pregnancy should be determined.