Bacterial infections in human immunodeficiency virus (HIV) infected patients may frequently develop into septicemia. Our study evaluated the bacterial pathogens isolated from hemocultures of HIV-infected patients at Siriraj Hospital and their antimicrobial susceptibility tests. The percentages of positive hemocultures were 24.64, 21.38, 23.88, and 28.46% in 1996, 1997, 1998, and 1999, respectively. Salmonella spp was the most pathogen isolated, followed by Escherichia coil (10.93%), Staphylococcus aureus (8.2%), coagulase-negative staphylococci (6.56%), nonfermentative gram-negative rods (6.01%), Pseudomonas aeruginosa (5.46%), Klebsiella pneumoniae (4.37%), and Enterobacter spp (4.37%). Salmonella, serogroup C was the most frequently isolated serogroup. It was sensitive to amoxicillin/clavulanate in 100%, ampicillin/sulbactam in 89%, cefazolin, cefuroxime, cefotaxime, ceftriaxone, ceftazidime, imipenem, gentamicin, amikacin, netilmycin, ofloxacin, and ciprofloxacin in 100%. The changing spectrum of bacteria and antimicrobial susceptibility patterns in HIV-1 infected patients may provide a guideline for the selection of appropriate drugs for treatment.