Objective: This study aims to investigate the role of inflammation in the pathophysiology of hyperemesis gravidarum (HEG).Methods: This prospective study was conducted in the Department of Obstetrics and Gynecology at Near East University Hospital betweenJuly 2019 and March 2020. The patients that were defined as HEG should have the following symptoms: Persistent nausea and vomiting, lossof >5% of pre-pregnancy body weight, presence of at least one positive ketonuria test in a random urine analysis, fetal heartbeat positivityat 6-13 weeks of gestation, and singleton pregnancy. Total blood count including white blood cell (WBC), neutrophil (NEU), lymphocyte (LYM),hemoglobin, hematocrit, and platelet and red cell distribution width (RDW) and platelet distribution width were analyzed. NEU-to-LYM (NLR)and platelet-to-LYM ratios (PLR) were calculated.Results: Forty-nine patients with HEG and 121 healthy women were evaluated in the first trimester of pregnancy. The healthy pregnantwomen and patients with HEG had similar age, gravida, parity, gestational weeks, and body mass index. WBC, NEU, RDW, C-reactive protein(CRP), and urinary ketone levels were statistically higher in the HEG group. There were no differences in terms of NLR or PLR.Conclusion: Measurement of inflammatory markers, such as WBC, NLR, PLR, and CRP levels, might provide valuable knowledge in HEGdiagnosis. NLR and PLR are acceptable, but CRP level is a better indicator for predicting the diagnosis and severity of the disease accordingto our study findings.