Preeclampsia is one of the major health problems causing maternal morbidity and mortality, complicating 3-8% of pregnancies. It has been suggested that the alterations in the coagulation and fibrinolysis play a role in the pathogenesis of preeclampsia. The markers of platelet activation include platelet count, platelet distribution width, mean platelet volume and plateletcrit.It was a case-controlled study which included a total of 60 patients (30 cases and 30 controls). Blood samples were collected and the platelet indices - platelet count, plateletcrit, mean platelet volume and platelet distribution width - were evaluated using the Sysmex XN1000 and compared between the two groups.The MPV and PDW also showed a significant difference (p>0.05) between the two groups, with a significant positive correlation with increasing blood pressure (MPV - r=+0.6126, p<0.05 and PDW - r=+0.6441, p<0.05). The PC and PCT had lower values in the preeclampsia patients, however the difference between the two groups was not statistically significant.The MPV and PDW showed a significant difference between the two groups and increasing values with increasing BP. However, the PC and PCT in our study did not show a significant correlation with preeclampsia. Thus, the platelet indices, mainly the MPV and PDW, which are economical and easily available, can be reliable in the prediction and early diagnosis of preeclampsia, as well as a marker for the severity of preeclampsia.