Background Agitated patients who present a danger to themselves or emergency medical services providers may require chemical restraints. Haloperidol is employed for chemical restraint in many emergency medical services. Recently, ketamine has been introduced as an alternate option for pre-hospital sedation. On-scene time is a unique metric in pre-hospital medicine that has been linked to outcomes in multiple patient populations. When used for chemical restraint, the impact of ketamine relative to haloperidol on onscene time is unknown. Objective To evaluate whether the use of ketamine for chemical restraint was associated with a clinically significant (.5 minute) increased on-scene time compared to a haloperidol based regimen. Methods Patients who received haloperidol or ketamine for chemical restraint were identified by retrospective chart review. On-scene time was compared between groups using an unadjusted student t-test powered to 80% to detect a .5 minute difference in on-scene time. Results 110 cases were abstracted (haloperidol = 55; ketamine = 55). Of the patients receiving haloperidol, 11/55 (20%) were coadministered a benzodiazepine, 4/55 (7%) received diphenhydramine and 34/55 (62%) received the three drugs in combination. There were no demographic differences between the haloperidol and ketamine groups. On-scene time was not statistically different for patients receiving a haloperidol-based regimen compared to ketamine (18.2 minutes, [95% CI: 15.7-20.8] vs. 17.6 minutes, [95% CI: 15.1-20.0]; p=0.71). Conclusion The use of pre-hospital ketamine for chemical restraint was not associated with a clinically significant (.5 minute) increased onscene time compared to a haloperidol based regimen.