Background: Chimeric antigen receptor T-cell therapies (CAR-T) have shown overall survival benefits in multiple hematological malignancies. Since Tisageneleleucel's first approval in 2017 for ALL in pediatric and young adults, FDA has approved 5 CAR-T cell product for adult hematological malignancies all in refractory/relapsed setting. Cellular therapies are associated with severe immune related adverse events (IRAE) like Cytokine release syndrome (CRS), Immune effector-cell associated neurotoxicity (ICANS), and Hemophagocytic Lymphohistiocytosis (HLH). Limited real world data available for CAR T-cell associated immediate toxicity. CMS approved recent updates in ICD coding leading to better identification of IRAE in discharge data. We used NIS 2020 database with updated ICD codes to quantify immediate inpatient toxicity related to CAR T-Cell therapy. Methods: We identified patients with CAR T-cell from discharge data by utilizing ICD-10 procedure codes of CAR T-cell therapy for 5 approved products. Codes for acute lymphoblastic leukemia (ALL), DLBCL (diffuse large B-cell lymphoma), multiple myeloma (MM,) Follicular lymphoma (FH), Mantle Cell Lymphoma (MCL) were used to identify the indication. Patients without these indications were categorized as "Others". Appropriate weights were applied to the analyses to obtain national estimates. We analyzed in-hospital outcomes i.e Length of stay(days), and mortality. CAR T-cell related specific toxicity i.e CRS, ICANS, and HLH were identified and reported along with other complications. Cost to charge ratio adjusted hospitalization cost were estimated. Results: 2240 patients were identified on review of the NIS 2020 with 61.1% males, 74.11% NHW, mean age 57.54 years (95%CI 55.31-59.78), while 42.19% of the patients were age ≥65 years. 47.1% patients had private insurance while 39.06 % had Medicare. CAR-T cell was used for DLBCL in 60.94%, FH 2.23%, MCL 7.37%, MM 8.93% and ALL 9.38% patients respectively. The use of CAR-T was approximately equally distributed among four geographical regions of the United States. The mean length of stay was 19.4 days (17.05-21.75) and in patient mortality was observed in 3.79% of the patient population. The IRAE noted were CRS (17.19%), ICANS (12.5%) and HLH (2.46%). Other significant complications among patients were sepsis (9.15%), acute kidney injury (15.85%), Seizures (1.79%) and intubation (4.46%). Overall cost associated with the CAR-T therapy was found to be 270,446.9 (235670.5 - 305223.3). Conclusions: CAR-T therapy has appeared as a breakthrough in cancer management. Demographic variation is still an important issue and majority of the patients treated are white and have private insurance. DLBCL remains the most common target for CAR-T. Neurological syndromes remain significant adverse effects of the therapy and should be closely monitored.