Surgical prophylaxis is one of the areas where antibiotics are used commonly. In this study it is aimed surgical prophylaxis appropriateness and determination of cost analysis in our hospital. The study was performed November 30-15, 2018. 108 patients who underwent surgery in general surgery, orthopedics and neurosurgery clinics have been included in this prospective study. Patient selection was based on the classification of clean and cleancontaminated. Demographics, features of the surgery, applied prophylactic antibiotics and surgical prophylaxis appropriateness were recorded in the forms. All patient information forms were evaluated by infectious disease specialists using the surgical prophylaxis guide. The costs of unnecessary antibiotics were determined. Mean age of 108 patients who underwent a surgical procedure was 52.4 years and 39.8% of the patients were male and 60.2% were female. Of the surgery procedures 75.9% (n:82) were clean and 24.1% (n:26) clean-contaminated. Preoperative 58.3% (63) unnecessary antibiotic prophylaxis was detected. Continuing prophylaxis at a prolonged time were used in 99 (91.7%) patients in the postoperative period. Cefazolin is the most commonly used agent for surgical prophylaxis. The cost of unnecessary and long-term antibiotic use was determined as ₺6983,69. In this study, the time of antibiotic prophylaxis were to be a big problem. Prophylaxis often starts very early and continues for days. The wrong practices in surgical prophylaxis lead to unnecessary antibiotics treatment to the patients and also burden to the budget of the country.