Cefoperazone was given parenterally to 10 patients (9 woman and 1 man, aged 19 to 75 years) with positive blood cultures for Salmonella typhi (9 cases) or Salmonella paratyphi A (1 case). Daily dosage was 0.5 g on the first day, 1 g on the second and 2 g on the third. Five patients had 4 g on the fourth day. Average time to defervescence was five days. There were no relapses. Cefoperazone is therefore satisfactory for treating typhoid fever, especially caused by ampicillin- or chloramphenicol-resistant bacteria.