Objectives: Serous otitis is one of the most common childhood illnesses due to exist of effusion in the middle ear. The reason of effusion is an increase negative pressure in the middle ear space. This effusion has different concentrations that vary from serous to mucus. The objective of our study was to compare the neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) in otitis media with effusion (OME) and the correlation of the effusion types in the middle ear with these ratios. Methods & Materials: This is a case-control study. Patients with OME that candidate for ventilation tube insertion were included in this study. Patients in the case group were divided into two groups of 64 cases, serous and mucus, according to the middle ear fluid viscosity, which were recorded by the surgeon after myringotomy. 64 healthy children, who applied for the routine examination and had blood count analysis, were included in the control group. In peripheral blood cells, the NLR and PLR are derived based on the absolute amount of lymphocyte and neutrophil and platelets. In this study, descriptive statistics were used to compare the mean of quantitative variables in 3 groups of ANOVA and to compare the qualitative variables, the x2 test was used. The analysis was done with the SPSS v22.0 software program. Significant statistical level was 0.05. Results: The NLR levels of the serous OME groups were significantly higher than the mucoid (p= 0.047) and control groups (p= 0.002). No significant difference was observed between the mucoid and control groups (p= 0.326). The PLR levels of serous OME groups were significantly higher than the mucoid (p= 0.003) and control groups (p= 0.002). Similarly, a significant difference was observed between the mucoid and control groups (p= 0.391). Conclusion: Neutrophil/lymphocyte rate and PLR were a predictive value for the OME and could be used as a useful laboratory parameter to determine the viscosity of the middle ear fluid.
