Objective Otitis media with effusion is an inflammatory disease characterized by fluid accumulation in the middle ear. The aim of this study is to investigate the predictive role of neutrophil, platelet, and eosinophil-to-lymphocyte ratio and mean platelet volume in adult patients having otitis media with effusion and to compare with control subjects; analyse whether they could be a potential predictor parameter to predict the disease progression. ( Sakarya Med J 2019, 9(2):3297-301 ). Materials and Methods In our study which was planned as “case-control study”, we retrospectively analyzed 69 patients (44 male, 25 female) between the ages of 18-50 having only chronic otitis media with effusion, and 69 age- and sex matched (between ages of 18-50; 38 male, 31 female) healthy controls. Study and control groups were compared with each other for MPV, neutrophil-to-lymphocyte, platelet-to-lymphocyte, and eosinophil-to-lymphocyte ratios. Results NLR, PLR, ELR and MPV values in the patient group were 1.97, 112.69, 0.08 and 7.75 and the mean value of the control group was 1.90, 114.58, 0.06 and 7.62, respectively. There was no statistically significant difference between the groups (p = 0.646, 0.843, 0.16, 0.769, respectively). Conclusion Although there are other studies in the literature, we think that these values do not have a predictive value in the diagnosis of EOM. It is clear that further studies with large numbers of subjects are needed.