Blood culture remains the best approach to identify the incriminating microorganisms when a bloodstream infection is suspected, and to guarantee that the antimicrobial treatment is adequate. Major improvements have been made in the last years to increase the sensitivity and specificity and to reduce the time to identification of microorganisms recovered from blood cultures.In some infections, the causative agents are only occasionally found in the blood, so a series of three or more blood cultures, as well as blood draws from different veins, can be performed to increase the chance of finding the infection. Blood cultures are incubated for several days before being reported as negative. Some types of bacteria and fungi grow more slowly than others and/or take longer to be detected if initially present in small numbers. A positive result indicates that bacteria were found in the blood (bacteremia). Other types of pathogens, such as fungi or viruses, may also be found in the blood culture. When a blood culture is positive, the specific microbe causing the infection is identified and susceptibility testing is performed to inform the healthcare professional which antibiotics or other drugs are most likely to be effective for treatment. It is important for nurses to remember that when new orders for both antibiotics and blood cultures are received, antibiotics should not be given before blood cultures are taken. The use of antibiotics as empiric therapy before taking a blood culture sample can affect test results, as well as the use of inappropriate antimicrobial therapy that can affect the outcome of treatment (prolonged stay or death). Administering antibiotics prior to taking a blood culture will affect the results and adversely affect the treatment plan. The aim of this paper is to show how the nurse is responsible for the pre-analytical phase of blood culture testing and how her knowledge and skills can influence the quality of blood culture test results. The method of preparing the space, accessories and the patient himself when taking the test, as well as proper storage and transportation, will be explained.