30 patients with different infections were treated with fosfomycin: 13 had urinary infections, 14 had pneumonial infections, 2 had staphylococcus osteomyelitis and 1 had staphylococcus septicemia. The antibiotic was administered in doses ranging from 100 to 230 mg/kg/day, with periods of treatment that lasted from 5 to 58 days. The doses were administered every 6 h by the oral or intramuscular route. A total of 35 organisms were isolated: 7 E. coli, 7β-hemolitic Streptococcus, 6 Proteus sp., 6 S. aureus, 6 S. viridans, 2 Klebsiella sp. and 1 negative coa-gulase S. aureus. All were sensitive to fosfomycin in vitro, as was revealed by the diffusion in discs method. The therapeutic results were good in 29 of the 30 cases (96.7%). There were no important side effects. A patient complained of a local pain in the area of the injection. The transaminases increased temporarily in 2 patients. One patient had a moderate eosinophilia while under treatment