11067 Background: Cytokine release syndrome (CRS) is a potentially life-threatening complication commonly seen in patients receiving chimeric antigen receptor (CAR)-T cell therapy, allogeneic stem cell transplant, or immunotherapies. This study aims to evaluate the inpatient burden outcomes of CRS leading to hospitalization in patients diagnosed with cancer. Methods: Hospitalizations for cytokine release syndrome (CRS) were identified using ICD-10 coding from the 2020 National Inpatient Sample (NIS), the largest all-payer inpatient database in the US. Only CRS patients with a co-diagnosis of cancer (identified using the Clinical Classification Software (CCS) coding) were included in this study. The underlying severity of illness index was used to verify CRS grading. Sampling weights were applied to generate nationally representative estimates. Results: In 2020, there were 4,765 hospitalizations coded with CRS. 27.2% of these admissions had a co-diagnosis of cancer (n=1,295) and were included in the final analysis. The top co-diagnoses in the patients with CRS without cancer were COVID-19 infection and sepsis. Hematologic malignancies had the highest incidence amongst cancer types (75.7%), the distribution was as follows: 29.6% with diffuse large B-cell lymphoma, 19.9% with acute lymphoblastic leukemia, 12.8% with multiple myeloma, 12.2% with acute myeloid leukemia, and 7.7% with mantle cell lymphoma. The most common procedures in oncology patients hospitalized with CRS were CAR-T cell therapy (29.3%), chemotherapy (28.6%), stem cell transplant (8.5%), or Blinatumomab bispecific antibody (5.4%). 11.4% of patients with CRS received tocilizumab. Of those that received tocilizumab, 10% were CRS grade 2, 56.7% were grade 3, 33.3% were grade 4. 51.7% of tocilizumab was given in the first 48 hours of admission. A minority of CRS patients required critical care interventions: 12.0% requiring intubation, 5.8% requiring vasopressor support, and 2.7% received dialysis. Overall, 10.4% of all oncology admissions with CRS resulted in death during hospitalization (n=135). Of these deaths, 92.6% were in the extreme severity of illness and 63.0% were CRS grade 4. Those with CRS who died during hospitalization had a significantly longer length of stay (24.6 vs 13.6 days, p<0.001). The overall median hospital charges of a CRS-related admission were $531,692. Conclusions: This study represents the inpatient burden of CRS-related admissions in patients diagnosed with cancer. CRS admissions are commonly seen in patients with hematologic malignancies, those undergoing CAR-T cell or immunotherapies (bispecific antibodies). CRS poses a significant healthcare burden, with average hospital charges being greater than 0.5 million US dollars per admission. About 1 in 10 patients with CRS died during hospitalization with higher mortality likely with severe CRS grades and longer length of stay.