Bacteremia is one of the major infections in orthotopic liver transplantation (OLT). The study of 83 adults who underwent OLT from 2001 to 2004, included patients followed prospectively from the day of transplantation to 4 weeks after the procedure by bacteriological cultures. The microorganisms were investigated according to standard National Committee for Clinical Laboratory Standards (NCCLS) procedures. Blood samples were examined in 59 recipients (71.1%) before and in 76 patients (91.6%) during the month after transplantation. Among 249 investigated samples, 96 were positive, as cultured from 19 recipients before OLT and 48 patients afterward. The most common were Gram-positive cocci (n = 71) and coagulase-negative staphylococci (n = 52), including methicillin-resistant coagulase-negative staphylococci (MRCNS). Enterococcus spp. occurred in 9 isolates (high-level aminoglycoside-resistant enterococci [HLAR] strains were cultured). We cultured the Enterobacteriaceae family (n = 16 isolates) and (n = 15 isolates), Gram-negative nonfermenting rods some of which were extended spectrum beta-lactamase producing [ESBL(+)] strains. The predominance of Gram-positive cocci was caused by CNS, and the use of prophylaxis to reduce Gram-negative bacteria. The increased rate of isolation of bacteria with multidrug resistance (MDR) to antimicrobial agents may be due to their frequent use for prophylaxis of bacterial infections in OLT. These MDR bacterial strains caused severe BSI after OLT.