Blood cultures submitted to Microbiology laboratory of Marmara University Hospital were reviewed for rate of true positive and false positive results according to patients, medical data and laboratory correlations. Out of 1957 blood samples (taken from 811 patients) 230 cultures (11.8%) from 98 patients have been found to be true positives and 73 cultures (3.7%) from 61 patients were interpreted as false-po- sitives. In 84.5% of blood samples taken from 652 patients no microorganism has been recovered. In regard with the number of patients yielding true positive (98) and false positive (61) cultures, results have also demonstrated that false positive rate was so high indicating in about one-third of the patients, blood culture experience was inappropriate (61 of 159).