Purpose The purpose of this study was to assess an institution’s heparin protocols in elderly and nonelderly adult populations to see if a response difference was observed. Methods This was a retrospective cohort study of hospitalized adults who were prescribed unfractionated heparin due to surgery, acute coronary syndrome (ACS), or deep vein thrombosis/pulmonary embolism (DVT/PE) from February 11, 2016, through August 1, 2017. Patients were divided into nonelderly adults 18 to 69 years of age and elderly patients 70 years of age or older. The anti-factor Xa (anti-Xa) level after protocol initiation was compared to the institution’s goal range of 0.3 to 0.7 IU/mL. Outcomes of each protocol in the elderly population were compared to outcomes in their nonelderly counterparts to determine if there was a difference in heparin response. Results A total of 325 patients were included in the analysis, comprising 150 elderly and 175 nonelderly adults. Elderly patients had a higher initial anti-Xa levels than did their nonelderly adult counterparts in the ACS, DVT/PE, and surgery protocols, with P values of 0.02, <0.001, and 0.01, respectively. Only the ACS protocol demonstrated increased frequency of above-target-level anti-Xa levels in the elderly (P = 0.03). Conclusion Elderly patients had significantly higher initial anti-Xa levels than did nonelderly adult patients across all protocols. This study identifies the need to further study elderly patients’ increased heparin sensitivity to determine if a separate dosing protocol is needed.