Clinical studies were performed on combination chemotherapy with Fosfomycin and Dibekacin. Sixteen patients with complicated urinary tract infections were treated with a combination of Fosfomycin (4 g/day, d.i.v.) and Dibekacin (200 mg/day, i.m.) for 5 days; and, 15 of them were clinically evaluated by criteria of UTI committee. The clinical effects proved excellent in 3 patients, good in 8 patients, and poor in 4 patients overall effective rate was 73.3%. Out of 19 strains isolated from the patients, 12 strains disappeared after the therapy. No side effect was observed in 16 cases. Clinical use of the combination chemotherapy with Fosfomycin and Dibekacin was thought to be effective and safe for patients with complicated urinary tract infections, because the combination acts not only synergistically, but also because Fosfomycin acts to protect against the nephrotoxicity induced by Dibekacin.