Background and objective: Surgical site infection (SSI) is defined as infections occurring within 30 days after a surgical operation or within one year if an implant is left in place after the procedure. Antibiotic prophylaxis formed as part of surgical care to reduce SSI. Antibiotic prescription pattern for SSI prophylaxis and it's concordance with American Society of Health-System Pharmacists(ASHP) guideline were evaluated throughout this study. Materials and method: This study was conducted in Imam Khomeini hospital, cancer institute. Patients with cancer who underwent abdominal surgery were included in this study. The information about type of antibiotic used for prophylaxis, dose, initiation time, and duration were collected during study. Compliance was assessed with the ASHP guideline for every aspect of antibiotic prophylaxis. SSI was assessed during 30 days after surgery. Results: All the patents needed antibiotic prophylaxis among them, only 103 patients received it. Antibiotic choice, dose and initiation time of prophylaxis were concordant with ASHP guideline in 36. 3%, 1. 6% and 60. 5%, respectively. Unlike the ASHP, the duration of prophylaxis was more than 24 hours in all patients. Finally, 32 patients experienced SSI during 30 days after surgical procedure. Conclusion: This study showed poor adherence to guideline in various aspects such as type, dose and duration of antibiotics for SSI prophylaxis. It is essential to implement interventions to improve the rational use of antibiotics in this setting.