The authors have studied a new antibiotic Tobramycin in 30 patients with acute infectious pulmonary disease, denominated type I, II and III, according to associated factors, severity and previous pulmonary alterations, being 29 patients included in type II and III. The pneumonia diagnosis has obeyed to clinical, laboratorial, radiological and microbiological criteria. The results after the Tobramycin therapy in 28 evaluable cases were: 3 failures and 25 therapeutic successes. The gram negative bacteria predominated among the causative pathogens and, in 14 patients, strains of Klebisiella Enterobacter group were isolated. The M.I.C. for the pathogenic isolated bacteria in acute pulmonary processes was less than 1,0 microgram/ml in 26 cases. Adverse reactions were observed in 13 patients, from which 9 have presented only laboratorial alterations. The remaining 4 patients have also presented clinical manifestations. These findings were similar to those reported for other aminoglicosides.