Abstract Introduction/Objective Comparisons of diagnostic testing across multiple health systems over multiple years are uncommon. Such comparisons would quantify variations in test use between health systems. Methods/Case Report Using the Vizient Clinical Database, we compared clinical laboratory and imaging utilization for hospitalized adult sepsis patients (N = 69,035) over three years (2017-2019) at 19 large academic-affiliated health systems across the United States. We used Medicare Severity Diagnosis Related Groups (MSDRG), employed by the US Centers for Medicare and Medicaid Services (CMS), and identified sepsis patients (MSDRG triplet 870/871/872). We stratified hospitalized sepsis patients by severity of illness (SOI) into high severity (MSDRG 870), moderate severity (MSDRG 871), and low severity (MSDRG 872) groups. SOI further categorizes patients within a diagnostic group, quantifying the extent of comorbid conditions and complications. We measured hospital length of stay (LOS), number of laboratory tests (CPT codes 80000-89999), and number of imaging studies (CPT codes 70000-79999). We divided the number of laboratory tests and radiology studies by mean hospital LOS (in days) to calculate laboratory tests and imaging studies per hospital day. Results (if a Case Study enter NA) Between health systems, lowest and highest values for laboratory and imaging utilization ranged from 50.1 to 141.3 tests per hospitalization and 1.4 to 7.2 studies per hospitalization, respectively. Differences in laboratory tests between health systems persisted after adjusting for SOI with low to high laboratory tests per hospitalization ranging from 127.8 to 405.7, 51.0 to 144.7, and 31.9 to 78.2, for high, moderate, and low SOI groups. Utilization ranges were smaller for imaging studies. After adjusting for hospital LOS, laboratory testing differences between health systems were more pronounced and with low and high laboratory test per day utilization of 6.5 to 24.3, 6.1 to 18.5, and 6.0 to 17.1, for high, moderate, and low SOI groups. Differences in radiology studies were not as pronounced after adjusting for LOS. Conclusion There is considerable variation among health systems in laboratory and radiology resource utilization for hospitalized sepsis patients. This variation persists, especially for laboratory testing, after adjusting for SOI and LOS.