Résumé : Gentamicin, carbenicillin, and the combination of gentamicin and carbenicillin were used at random to treat severe bacteriologically proven infections caused by gram‐negative bacilli. In 68 patients with disseminated cancer, favorable results were observed in 13 out of 23 (57%), 11 out of 22 (50%), and 19 out of 23 (83%) of the patients, respectively. These results correlated well with the higher antibacterial activity found in sera of patients who received the combination of gentamicin and carbenicillin as compared to sera of patients treated with carbenicillin or gentamicin alone. Gentamicin was used in this series at doses ranging from 6 to 8.5 mg/kg/day without the development of serious ototoxicity, or renal toxicity. Copyright © 1973 American Cancer Society