BACKGROUND Th2/Th1 mix pathological pathway may be seen as a common set of low eosinophilic phenotype in severe allergic asthma. This may affect omalizumab treatment response. In our study, we aimed to investigate whether eosinophil count (EOS) and percentage (EOS%), eosinophil lymphocyte ratio (ELR) and neutrophil lymphocyte ratio (NLR) may predict omalizumab treatment. METHODS Patients who received omalizumab treatment at least for one year in our allergy clinic were screened retrospectively. Baseline hemogram parameters, pre- and post-treatment emergency admissions, annual attacks requiring steroid use, hospitalizations, spirometric changes, and asthma control tests (ACT) were recorded. According the global efficacy assessment (phisician's GETE) scale patients was recorded as responder and nonresponder. By looking at EOS, EOS%, ELR and NLR distributions in these groups, the role of these parameters in representation of the treatment efficacy was investigated. RESULTS The study was carried out with 83 patients, 77.1% of whom were women with an average age of 50.03 ± 10.7. While ACT scores and FEV1, FEF25-75 was significantly increased, the number of emergency admissions, annual attacks and hospitalizations decreased significantly (p<0.05). The rate of patients signed as responder was 75.9%, while the rate of nonresponder was %24.1. When the two groups were compared, it was found that the EOS, EOS% and ELR were significantly higher in the responder group. The cut-off values according to the ROC curve were determined as 0.12, 310/ml and 3.1% respectively. Considering the sensitivity (58.73%); specificity (85.00%); positive predictive value (92.50%), it was determined that ELR was a more valuable test. CONCLUSIONS Instead of expensive and invasive methods for predicting the response of omalizumab therapy in severe allergic asthma, the ELR is correlated with treatment response and giving hope to be easier way to reach.