The aim of present study was retrospective analysis of the frequencies of occurrence of the most common microorganisms isolated from blood cultures in the Medical University in Gdańsk from 2000 to 2002. The blood patterns were taken from adult patients with symptoms suggesting bacteriemia. During the 3 year study period 31788 blood samples were obtained, of which 5520 (17.37%) were positive. The number of Gram-positive bacteria isolated from blood increased and the rate of Gram-negative bacteria decreased over the study period. In addition the increase of frequency of Candida, VRE and Escherichia coli was noted. The number of infections caused by MRSA and Gram-negative ESbetaL+ diminished during time of observation. Acquaintance on the most frequently isolated organisms from blood patterns and they antimicrobial susceptibility should guide the choice of empiric antimicrobial regimens for patients with bacteriemia.