Objectives: The study was designed to determine the accuracy of using systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), and increase of blood pressure (BP) to predict Preeclampsia (PE). Materials and Methods: We examined 300 normotensive and 100 PE pregnancies divided in two subgroups: mild (n=67) and severe (n=33) PE. The patients had a BP check in first and second trimester (SBP, DBP, and MAP). Results: We found out significant difference between the groups, but what is more important is that the difference in BP values (especially diastolic and MAP) existed before the pathological increase of the BP above the normal values. This was happening most often after 31 wg (at 92.5%) and less often after 26 wg (at 7.5%) at the pregnancies with mild PE while at the pregnancies with severe PE, 18,2% had increased tension after 21 wg; 24% in the period of 26-30 wg and 57.58% after 31 wg. Conclusion: Based on the results we could conclude that when BP is measured in the first or second trimester of pregnancy, the MAP is a better predictor for PE than SBP and DBP.