The aim of this study was to assess whether multiresistant gram-negative bacteremias (MRGNB) were associated with specific risk factors for higher mortality than sensitive gram-negative bacteremias. Two groups of subjects: (51 cases and 102 controls) were matched for sex, age, underlying disease, and neutropenia. There were no significant differences in the incidence of cytotoxic chemotherapy administered, vascular catheter insertion, catheter as source of bacteremia, and etiology of bacteremia. The proportion of Klebsiella-Enterobacter, Pseudomonas aeruginosa, Acinetobacter spp., and Stenotrophomonas maltophilia was similar in the two groups. Prior surgery (21.6% vs 7.9%, P < 0.05) was significantly associated with sensitive gram-negative bacteremia. Previous prophylaxis with ofloxacin (45.1% vs 24.5%; P < 0.05) and prior therapy with broad-spectrum antibiotics (41.2% vs 27.5%; P < 0.05), such as first and second generation cephalosporins (19.6% vs 7.8%; P < 0.05), third generation cephalosporins (41.2% vs 13.7%; P < 0.01), aminoglycosides (39.2% vs 9.8%; P < 0.01), ofloxacin (11.8% vs 2.0%; P < 0.005), and imipenem (19.6% vs 2.0%; P < 0.001) were significantly more frequently observed among cases than controls. Cases (patients with bacteremia due to multiresistant gram-negative bacteremias) were also significantly more frequently infected with bacteria resistant to ceftazidime (68.6% vs 17.6%; P < 0.001), amikacin (52.9% vs 7.8%; P < 0.001), imipenem (50.1% vs 23.5%; P < 0.05), ciprofloxacin (32.1% vs 5.9%; P < 0.001), and piperacillin (41.2% vs 7.8%; P < 0.01). With regard to outcome, attributable mortality was similar (15.7% vs 13.8%; not significant) in the two groups; however, cure rates were lower among cases (patients infected with MRGNB) because crude mortality was higher in cases (35.3% vs 13.8%; P < 0.01) than in controls.