Summary Of 47 patients with Klebsiella pneumoniae bacteraemia admitted to the Hillbrow Hospital, Johannesburg during a period of 18 months, 31 were males and 16 were females. Features predisposing to illness were found in 89·4% patients, chronic alcoholism, neoplastic disease and diabetes mellitus being the most common. Twenty-five infections were acquired in hospital and 22 in the community. Most patients (59·6 %) had pneumonia. All isolates of K. pneumoniae were resistant to ampicillin (100%); several (42·6%) were resistant to other antibiotics also. The overall mortality rate was 55·3%. A higher mean initial blood pressure and lower concentrations of serum urea and bilirubin were found in survivors. None of the 28 patients, surviving more than 48 h who received combined therapy with an aminoglycoside and a β-lactam antibiotic (to which the organism was susceptible) died. Among the remaining patients treated with either an appropriate β-lactam agent alone, an appropriate aminoglycoside alone or ciprofloxacin the combined mortality rate was 83·3 % ( P = 0·007).