Between Mid-1996 and Mid-1998, 238 bacteria strains isolated from blood culture of adult patients of Tikur Anbassa Hospital, Addis Ababa, Ethiopia, were retrospectively analyzed for their frequency of isolation and antibiotic susceptibility pattern. Coagulase negative Staphylococcus aureus (CNS) were isolated with the highest frequency 103 (43.3%), followed by Staphylococcus aureus 34(14.3%), Klebsiella spp. 23(9.7%), E. Coli 19(8.1%), Pseudomonas spp. 16(6.7%), Acinetobacter spp. 12(5%), Salmonella spp. 9(3.8%) and miscellaneous group 22(9.2%). The gram positive bacteria constituted 149(62.6%) of the total blood isolates. It is suggested that a proportion of both the gram positive and gram negative isolated represent contaminants at blood sampling. Rates of susceptibility for gram positive range from 12% to 76%, and for gram negatives range from 8% to 46%. In general, rates of susceptibilities to all antibiotics tested for gram negatives were very low as compared to gram positives. Among the gram positives, more than half of the isolates were sensitive to amoxicillin + clavulanic acid, ampicillin, carbenicillin, cephalothin, chloramphenicol, erythromycin and methicillin. Gram negative bacteria showed a high rate of resistance to many of the commonly prescribed antimicrobial drugs: amoxicillin + clavulanic acid (65%), ampicillin (87.5%), amoxicillin (91.7%), carbenicillin (75%), cephalothin (73.6%), chloramphenicol (65%), gentamicin (55.6%), kanamycin (54%), trimethoprim-sulphamethoxazole (64%) and tetracycline (61%). If generally considered, only gentamicin and kanamycin were relatively effective against gram negatives. Over 85% Salmonella spp were sensitive to chloramphenicol and trimethoprim-sulphamethoxazole. Compared to previous studies done in the same hospital, there is a higher rate of antibiotic resistance for most types of blood culture isolates particularly for gram negatives. The rational use of drugs should be practiced in order to minimize the spread of drug resistant bacteria.