Copyright © 2021 by Türkiye Klinikleri. This is an openObjective: This study aims to evaluate the effects of omalizumab on hematological parameters and inflammation biomarkers in patients diagnosed with chronic spontaneous urticaria (CSU). Material and Methods: The records of 109 (76 women and 33 men) patients, who were treated with omalizumab with the diagnosis of CSU were retrospectively examined. In addition, the pre-treatment and post-omalizumab treatment periods were evaluated in CSU patients by comparing hematological, inflammatory and biochemical parameters. The data of these patients were compared to a healthy control group with similar characteristics such as age and gender. Results: C-reactive protein (CRP), neutrophil (NEU), and monocyte values were significantly higher in patients with CSU, while basophil values in control individuals. The comparison of the measurements of the patients before and after omalizumab treatment revealed a significant reduction in CRP, white blood cell (WBC), NEU, and platelet (PLT) levels. WBC, NEU, and eosinophil levels were found to be significantly reduced in responders compared to non-responders to treatment. Conclusion: The evaluation of CRP, NEU, PLT levels are found to be important to show the activity of the disease in CSU. We think that these inflammatory markers are important in the follow-up of CSU and omalizumab treatment. We think that these inflammatory markers are important in the follow-up of CSU and omalizumab treatment. Our results will contribute to the medical literature to establish both the mechanism of action of omalizumab and the parameters used in the follow-up of omalizumab therapy in patients with CSU.