Overall 30-day mortality among patients with nosocomial bacterial infections was analysed according to antibiotic susceptibility in an 800-bed hospital. Survival analysis identified three factors associated with an increased mortality rate: (1) a longer interval between admission and onset of infection; (2) bacterial resistance; and (3) the severity of the initial illness in the intensive care unit. The increased mortality rate associated with antibiotic resistance was observed for all bacterial species with the exception of Gram-positive cocci, and remained significant or near-significant regardless of the hospital ward.