Background & Aim: Blood cultures are one of the most important laboratory tests in diagnosis serious infections. Like any other test false- positive results is a limitation to this method. Contaminated blood culture can cause diagnostic dilemmas for clinicians. The aim of this study was to evaluate the effect of teaching correct sampling method on decreasing contamination of blood culture of the patients who are admitted in Khorram abad’s Ayat-ollah Madani hospital.
 Material and Methods: This study was a semi experiment trial which historical control group describes the differences between the blood samples withdrawal for blood culturing in the first half of 2007, which were collected only alcohol for disinfection the first half of the year 2008 with using alcohol-providone - iodine and needle replacements after proper staff training for contamination in blood culturing at the Ayatollah Madani Hospital's wards.
 Results: Our results showed that, coagulase -negative staphylococci were the most common microorganisms blood culture contamination before (71.53%) and after (65.85%) of education, and (5.17%) contamination rate after education was significantly lower than before (14.97%) (p < 0.001).
 Conclusion: The current study suggests that use of this method (alcohol - povidone-iodine and changed needle) reduces blood culture contamination and will lead to better isolation of microbial pathogens and consequently easier diagnosis and treatment.