BACKGROUND: Costs of care are increasingly important in healthcare policy and, more recently, in clinical care in the emergency department (ED). We compare ED resident and patient perspectives surrounding costs in emergency care. METHODS: We conducted a mixed methods study using surveys and qualitative interviews at a single, academic ED in the United States. The two study populations were a convenience sample of adult ED patients (>17 years of age) and ED residents training at the same institution. Participants answered open- and closed-ended questions on costs, medical decision making, cost-related compliance, and communication about costs. Closed-ended data were tabulated and described using standard statistics while open-ended responses were analyzed using grounded theory. RESULTS: Thirty ED patients and 24 ED residents participated in the study. Both patients and residents generally did not have knowledge of medical costs. Patients were comfortable discussing costs while residents were less comfortable. Residents agreed that doctors should consider costs when making medical decisions whereas patients somewhat disagreed. Additionally, residents generally took costs into consideration during clinical decision-making, yet nearly all residents agreed that they had too little education on costs. CONCLUSION: There were several notable differences in ED patient and resident perspectives on costs in this U.S. sample. While patients somewhat disagree that cost should factor into decision making, generally they are comfortable discussing costs yet report having insufficient knowledge of what care costs. Conversely, ED residents view costs as important and agree that cost should factor into decision making but lack education on what emergency care costs.