Abstract(#br)Aim(#br)Hyperemesis gravidarum (HG) can be defined as intractable nausea and vomiting leading to electrolyte imbalance, ketonuria, nutrition deficiency and weight loss. Inflammation is known to play a crucial role in HG and many inflammatory markers have been studied to achieve early diagnosis. We investigated the association of the platelet to lymphocyte ratio and plateletcrit with the presence and severity of HG.(#br)Methods(#br)We retrospectively enrolled 433 pregnant women with a diagnosis of HG and 160 gestational age matched healthy pregnant women, who were admitted to a large tertiary research and training hospital between January and December 2015. Patients were divided into three groups: mild ( n = 147), moderate ( n = 153) and severe ( n = 133), according to HG... severity. Age, gestational age, gravida, parity, height, weight and laboratory parameters, including complete blood count, were recorded from patients’ medical records.(#br)Results(#br)The platelet to lymphocyte ratio and plateletcrit were both higher in the HG groups compared with controls ( p < 0.001). There was statistically significant difference in plateletcrit between the mild–moderate and moderate–severe HG groups ( p < 0.001). The area under curve for neutrophil to lymphocyte ratio, platelet to lymphocyte ratio and plateletcrit were 0.64, 0.68 and 0.68, respectively, with p < 0.001. Neutrophil to lymphocyte ratio > 3.9, platelet to lymphocyte ratio > 121.2 and plateletcrit > 0.20 were significantly related with an increased risk of HG.(#br)Conclusion(#br)The platelet to lymphocyte ratio and plateletcrit are effective inflammatory markers for predicting the presence of HG. Plateletcrit level could also be used to determine HG severity.