Our objective was to characterize the tasks of emergency radiologists and emergency physicians and quantify the proportion of time spent on these tasks to assess their roles in patient evaluation. Our study involved emergency radiologists and emergency physicians at an urban academic level I trauma medical center. Participants were observed for continuous 2-h periods during which all of their activities were timed and categorized into the following tasks: patient history, patient physical findings, assessment/plan, procedures, technical/administration, paperwork, and personal time. We performed multivariate analyses to compare the proportion of time spent on task categories between specialties. Twenty physicians (10 emergency medicine and 10 radiology) were observed for a total of 146,802 s (2,446.7 min). Radiologists spent a significantly larger combined proportion of time on determining physical findings and paperwork than emergency physicians (61.9 vs. 28.3 %, p<0.0001). Emergency physicians spent a significantly larger proportion of time than radiologists on determining patient history (17.5 vs. 2.5 %, p=0.0008) and assessment/plan (42.3 vs. 19.3 %, p<0.0001). Both specialties devoted minimal time toward personal tasks. Radiologists play a major role in the diagnostic evaluation of a subset of acute patients, spending significantly more of their time determining physical findings than their emergency physician counterparts.