Introduction: North American practice guidelines for empiric antibiotic selection in the treatment of epididymitis are based on very small studies. These guidelines recommend antibiotic selection based on age. This study’s objective was to determine if culture results in a Canadian emergency department population with acute epididymitis support these guidelines. Methods: We conducted an electronic health records review ED patients with a discharge diagnosis of epididymitis. All patients who presented to two emergency department sites of the Ottawa Hospital from 2012 through 2014 were included. Data collected were patient age, urine culture results, results of urine or urethral swab nucleic acid amplification test (NAAT) for gonorrhea or chlamydia, and results of scrotal ultrasound. Ultrasound radiology reports were independently reviewed by two authors and classified as positive, negative, or indeterminate. Results: We identified 379 cases of epididymitis. There were 169 patients aged 18-35 years, and 202 patients over 35 years. The rates of positive urine culture, in the under 35 and over 35 population respectively, were 5% and 42% (p<.0001). The rates of positive NAAT were 10% and 4% (p=.43). Ultrasound was performed in 252 patients; 160 (63%) were positive. There was no significant difference in the rates of positive urine culture or NAAT between the ultrasound-positive patients and patients who had negative, indeterminate, or no ultrasound. Conclusion: Our findings are not concordant with clinical practice guidelines. While the over 35 age group had a statistically higher rate of positive urine culture, the rate of positive NAAT was not different from the younger group. Both urine culture and NAAT are usually negative in the under 35 group. Positive culture rates are not higher in the subgroup of ultrasound “proven” epididymitis. Physicians should exercise clinical judgement in selecting empiric antibiotics for patients with epididymitis; basing choice on patient age alone may not be appropriate.