Objective: Patients seen in a hospital emergency department (ED) require acute care. There is no time to culture an infection for a specific antibiotic. Therefore, broad spectrum antibiotics are used most commonly for the unknown infections. It is the purpose of this project to examine physician choices of antibiotics, and the patient conditions for which they are prescribed. Methods: Data was collected in a mid-sized, urban hospital for a six month period. All antibiotics prescribed to the patients during this time period were recorded, a total of approximately 3100 prescriptions. Because the patients have very different complaints in the ED, it is difficult to isolate specific diagnoses to determine whether different diagnoses result in different antibiotic prescriptions. To handle this problem, we reduce the patient diagnoses to ten clusters to determine whether there is uniformity of prescribing within the clusters. Results: Levaquin was prescribed for approximately 40% of the patients receiving antibiotics in the hospital ED followed by Azithromycin and Cefotaxime at 10%. Vancomycin was used for 8% of the antibiotic prescriptions as was Piperacillin/Taxobactam (Zosyn). However, the prescriptions were not uniform across physicians. In particular, one physician favored Zosyn over Levaquin while another used as much Cipro as Levaquin. A total of 8 antibiotics account for 96% of the total use. Two of the least used include Linezolid and Tobramycin, both of which are expensive and should have a definite culture to support use. Although physicians differed considerably in their prescribing habits, there was no statistical difference in the patient conditions treated. Conclusion: Different physicians have different antibiotic prescribing habits. It is important to examine the prescribing to reach a consensus of best practices in the ED.