Rapid methods of determining microbial contamination are needed in suspecting contaminated banked blood or other blood products. In this study, we experimented contaminated blood units with 122 strains of bacteria and fungi. After innoculation, a comparison between ESP Blood Culture System (Difco Laboratories Inc., Detroit MI), BacT/Alert (Organon Teknica, Durham, NC) and Bactec 9240 System was made for their efficiency in the detection of microbial contamination. Experimental data showed a diagnostic relevance of these automated systems with no significant differences in time detection of microbial contamination between the three methods under comparison.