Aim: Although the relationship between red cell distribution width (RDW) and hypertension has been well documented, there is an absence of data on the association between RDW and preeclampsia. In the present study, we have aimed to investigate the correlation of RDW with preeclampsia and its severity. Methods: The study population consisted of 52 (35 mild and 17 severe) patients with preeclampsia and 50 control pregnancy patients. For the entire study population, baseline RDW was measured using an automatic blood counter. Results: Although there were no significant differences between the preeclampsia group and the control group in terms of hemoglobin and platelet counts, the RDW (14.1 +/- 1.1 vs 16.9 +/- 1.7, P <.001), systolic and diastolic blood pressure, proteinuria, white blood cell, and high-sensitivity C-reactive protein levels were significantly higher in the preeclampsia group. Moreover, subgroup analysis revealed that RDW levels were significantly increased in patients with severe preeclampsia when compared to the patients with mild preeclampsia (18 +/- 1.5 vs 16.4 +/- 1.5, P <.001). Conclusion: Our study results revealed that RDW levels were associated with both the presence and the severity of preeclampsia.