Clinical efficacy and safety of piperacillin were evaluated in 30 patients with a severe aspiration pneumonia admitted in our intensive care unit from july 1987 to december 1988. 20 women and 10 men (with a mean SAPS: 14) had a right pneumonia in 17 cases, left in 6, bilateral in 7 cases. A pathogen was isolated in 18 patients by protected distal catheterism, in 3 patients by blood cultures. 25 patients cured. However with a high isolation of Staphylococci it appears reasonable to associate piperacillin with an aminoglycoside before the obtention of bacteriological results.