Introduction: Nearly 50% of Canadians will develop cancer in their lifetime (1), and the vast majority of those with cancer will visit the emergency department (ED) in their last 6 months of life (2). Considering the aging population, improvement in cancer survival and current practice of managing cancer in outpatient settings, cancer-related emergencies are becoming a significant aspect of emergency medicine. The presenting symptoms and rates of hospitalization for cancer-related ED visits have largely been established. The current study characterizes the patterns of ED utilization and time-course of events for cancer-related ED visits following same-day outpatient oncology appointments resulting in admission to hospital compared to those not admitted. Methods: A retrospective chart-review was used to identify 231 adult patients who visited the ED at a large academic hospital (i.e., Toronto General Hospital) following a same-day outpatient oncology appointment at an affiliated cancer centre (i.e., Princess Margaret Hospital) from March to May 2019, using administrative data. Results: All visits occurred on weekdays (avg = 4 visits/d) and 57% of visits resulted in hospitalization. Between those admitted and not admitted to hospital, there was no difference in triage time [17:23 + 0:14 vs. 17:01 + 0:20 h, p = 0.47; mean(SD)]. Visits resulting in hospitalization were more urgent (median CTAS score = 2 vs. 3, p < 0.001) and required more consultation services (64 vs. 17 % of visits, p < 0.001), but did not differ for imaging (36 vs. 33 % of visits, p = 0.63). The length of stay in the ED was longer for those admitted [16.6(0.9) vs. 5.3(0.3) h, p < 0.01), they waited longer for their initial assessment [2.6(1.9) vs. 1.8(1.3) h, p < 0.01) and spent 10.1(9.9) h waiting for a bed on the ward. There was no difference in time from initial assessment to disposition, imaging or consult reports (p > 0.05) between groups. The patients transferred from oncology clinics were triaged at 17:13(0:11) h compared to 13:56(0:03) h for all ED visits during the same time frame. Conclusion: Most patients sent from oncology clinics to the ED are admitted, and when admitted they spend an additional 10 h waiting for a bed on the ward. These patients tend to arrive later in the day compared to other ED patients. Understanding utilization patterns and time-course of events allows for objective identification of quality improvement initiatives. 1 Canadian Cancer Society, 2015 2 Barbera et al. CMAJ, 2010