Objective: Surgical site infection (SSI) is the second most common cause of hospital infections and is responsible for nearly 15% of these infections. Due to an increase in bacterial resistance, the lack of similar studies in our country, we conducted a study.

Methods: in this clinical trial, The patients were randomly divided into two groups: the case group that received intravenous antibiotics for 24 hours (2 gr cefazolin during induction of anesthesia and then 2 gr every 8 hours until 24 hours) and the control group which received standard antibiotic regimen (2 gr cefazolin during induction of anesthesia and then 1 gr every 6 hours until 48 hours, then 500 mg oral cephalexin for 48 hours up to one week.

Results: The number of patients participating in the study was 218, of which 167 were male (%76.6) and 51 female (% 23.4), respectively. The mean patient age 56.20 ± 13.40 years, respectively. Between two groups there was no significant difference in the frequency of fractures. In this study, there was no significant difference between age and gender of patients in the two groups. Finally, there was no statistically significant difference between the site and type of fractures.

 Discussion: This study showed that using a one-drug protocol is recommended for prevention of surgical site infection in internal fixation of closed fractures. In addition, using intravenous antibiotics reduces patient costs than those which is administered intravenous and oral together.