Introduction:Antibiotics are among the most commonly prescribed drugs today.Currently,microbial resistance is a global problem,causing multidrug-resistant bacterial infections as well as the spread of resistant microorganisms.Given the importance of prescribing appropriate antibiotics and the importance of antibiotic testing in prescriptions by physicians,in this study we sought to determine the pattern of antibiotic use over a six-month period.The emergency physicians' use of the results of the antibiogram test was also evaluated,and the possible association of underlying diseases with their antibiotic use was assessed.Methods:After preparing the proposal and the questionnaires,obtaining the necessary permits,the project was implemented in the emergency department of Baqiyatallah Hospital.All participants in the study were receiving antibiotics who were admitted to the emergency department for at least 48 hours.The data and their information were completed in the questionnaire and after the end of the 6-month period,the data were statistically analyzed.Results:The results of the study showed that the rate of E-coli infection was the highest among the study participants.The results of the antibiogram test showed that the majority of people were sensitive to Nitrofurantoin,Levofloxacin and Metronidazole,while most people resisted Trimoxazole.The most commonly prescribed antibiotic in the emergency room was Ceftriaxone,followed by a combination of Vancomycin and Meropenem.There was no significant statistical relationship between antibiotic use and final diagnosis,and there was a statistically significant association between antibiotic use and underlying renal disease.High percentage of cases(36.6%),the results of antibiogram testing in emergency room were not used during this6-month period.Conclusion:In general,the most antibiotics prescribed in the emergency room during the6-month study period were ceftriaxone