In this prospective study, we evaluated contamination of surgical fields in open heart operations by salvaged blood culture used in autologous transfusions device (Cell Saver 5, Heamonetics Corp., Braintree, MA, USA). And also, we prospectively investigated an efficacy of pre- and intra-operative prophylactic antibiotics administrations (cefazolin). Thirty patients undergone open heart surgeries with median sternotomy enrolled in this study. The patients were divided into two groups, group A (n = 15); without prophylactic antibiotics administration, group B (n = 15); with pre- and intra-operative prophylactic antibiotics administrations. Blood samples were drawn through the right atrium after the discontinuation of CPB and from salvaged blood bags. Bacterial growth was detected in 80.0% of salvaged blood samples in group A, 86.7% in group B (p = 0.62). Whereas no bacterial growth detection in blood samples though the right atrium. Quantitative estimates of contaminations showed 1.06 +/- 1.41, 0.90 +/- 1.24 cfu/ml, respectively (p = 0.22). Although bacterial growth rate were not statistically significant difference between groups, detective rate of Staphylococci was remarkably decreased (p = 0.005) in group B. Pre- and intra-operative prophylactic antibiotics administrations were effective for Staphylococci, but not whole microorganisms. In conclusion, salvaged blood used in autologous transfusions was highly contaminated and it suggests that surgical fields were not clear. Prophylactic antibiotics administrations were effective especially for Staphylococci.