Background: Preeclampsia is one of the complications of pregnancy that endangers the life of the mother and the fetus. This complication accounts for 18% of maternal mortality and is the second leading cause of maternal mortality in Iran. Various studies have shown the important role of platelets in the pathogenesis of preeclampsia. Objectives: This study was conducted to evaluate platelet parameters in patients with preeclampsia compared to healthy pregnant women who were referred to Ganjavian hospital in Dezful city in 2019. Methods: In this study, which is a retrospective case-control study, the files of women who gave birth in Ganjavian hospital in 2019 were examined. The files of the case group, which included people with preeclampsia, were selected as available samples (104 people), and the control group, which included pregnant women without preeclampsia, were randomly selected using a table of random numbers (104 cases). Criteria for entering the study in the group with preeclampsia included BP ≥ 140/90 mmHg, proteinuria of more than 300 mg in 24-hour urine or 30 mg consistently in random urine samples, and gestational age over 20 weeks. Also, people with any underlying disease, such as diabetes, chronic hypertension, known platelet disorders, multiple birth, and drug use (heparin, aspirin) in the group with preeclampsia were excluded from the study. The data of this study were analyzed using SPSS software version 20, and independent t-test, and Mann-Whitney U test at a significant level lower than 0.05. Results: There was no statistically significant difference in demographic factors between the two case and control groups. There was a statistically significant difference between the mean hemoglobin in healthy women 11.91 ± 1.30 and preeclampsia 10.89 ± 1.09 (P < 0.0001). Also, according to the findings, the individuals of the two groups had a significant difference in terms of mean platelet volume (MPV): healthy women: 10.79 ± 1.24 and preeclampsia women: 12.98 ± 1.16 (P < 0.0001). Also, the results of the Mann-Whitney U test showed that there was a statistically significant difference between the number of platelets in healthy women (284.52 ± 60.58 mm3) and preeclampsia women (149.30 ± 30.38 mm3) (P < 0.0001). Conclusions: Considering the importance of reducing the complications and mortality of pregnant mothers, early detection of changes in platelet factors during pregnancy can be a predictive factor in identifying people at risk for preeclampsia.