Sixteen patients, 9 to 81 years old, with Gram-negative septicaemia have been treated with cefotaxime. In all cases, the patients were hospitalised in an intensive care unit for a severe infection distinct from septicaemia. Cefotaxime was given alone to 11 patients and was administered by infusion over 20 to 30 minutes, every 4 or 6 hours, in a daily dose of 67 to 94 mg/kg to patients with normal of subnormal renal function. Gram-negative pathogens were sensitive to cefotaxime (MIC less than 1 mcg/ml in most cases). A clinical cure was obtained in 14 patients. In all the cases, tolerance was good. The very low MIC's of cefotaxime and the results in severe Gram-negative septicaemia justify the use of cefotaxime in monotherapy, in patients with severe life-threatening infections, when blood cultures appear to be positive for Gram-negative pathogens, even without awaiting antibiograms.