Surgical site infections (SSIs) are the most common and costliest healthcare-associated infections. Antibiotic prophylaxis plays an important role in preventing SSIs, especially for clean and clean -contaminated wounds. Despite evidence of effectiveness and availability of guidelines, antibiotic prophylaxis adherence is often suboptimal. This descriptive cross-sectional study was conducted on 311 medical records of patients undergoing surgeries with clean or cleancontaminated wounds at 5 surgery departments at University Medical Center from January to April, 2017. The appropriateness of antibiotic prophylaxis usage was assessed using guidelines from ASHP, Vietnam's Ministry of Health or University Medical Center. Antibiotic prophylaxis was indicated in 99.3% of cases. The mean duration of postoperative use was 3.4 ± 2.6 days. Overall adherence to antibiotic prophylaxis guidelines was observed in 4.8% of procedures. The proportion of cases with appropriate adherence to antibiotic choice, dosing, timing of the first dose, redosing and duration of prophylaxis were 34.1%, 64.0%, 92.0%, 94.2% and 49.2%, respectively. Department of Obstetrics and Gynaecology, wound classification, length of surgery, antibiotics covered by Health Insurance were found to be significantly associated with the appropriateness of antibiotic choice. Adherence to antibiotic prophylaxis guidelines at University Medical Center was low within the study period. The Antibiotic stewardship program should be enhanced and actions to ensure Health Insurance coverage for all antibiotics used for prophylaxis should be implemented to improve the effectiveness and appropriateness of antibiotic prophylaxis.