Background: Use of costly emergency department (ED) resources is high amongst oncology patients. However, many oncology patients who visit the ED are discharged home without admission to an inpatient setting. A better understanding of why this group of patients presents to the ED can inform alternative interventions to shift care to less costly settings and reduce ED utilization. Methods: We conducted a review of administrative data at Brigham and Women’s Hospital (BWH) that serves as the ED for patients undergoing cancer treatment at the Dana Farber Cancer Institute. We identified oncology diagnosed patients that presented to the ED between 9/1/2011 and 9/30/2012 (n=6,035 unique visits). We focused our analysis in those patients ultimately discharged home, directly discharged (Home n=1647) or after an ED observation stay < 24 hours (ED Obs n=379) to evaluate opportunities for improvement. We then reported charges, cancer type, primary ED discharge ICD-9 code, and tests ordered per ED visit by disposition status. Results: We found that 34% of the ED encounters (n=2,026) were ultimately discharged home (directly discharged or after an ED observation stay). Among them, the average charge per visit for these patients varied from $3,304 (SD= 2,734) for Home to $10,951 (SD= 6,540) for ED Obs. 73% (n=1,473) of these patients had solid tumor diagnoses. The five most common solid tumor diagnoses associated with these patients were gastrointestinal (16%), gynecologic (12%), genitourinary (10%), breast (10%), and thoracic (9%). The most common ICD-9 codes associated with these patients’ admissions were abdominal pain (9%), fever (5%), dyspnea (5%), chest pain (3%), and nausea (3%). Of these outpatients, 53% (n=1,066) had at least one radiologic test performed, the most common tests being chest x-ray in 41% and CT scans in 16%. Conclusions: About 1 in 3 cancer patients who present to the ED are not admitted to an inpatient setting, representing potentially avoidable costly ED visits. Most of these patients are represented by five solid tumor diseases. Improved alternative outpatient access and management strategies of symptoms such as abdominal pain, dyspnea, and nausea in these patients may reduce ED utilization in this patient population.