A study was made of the activity of fosfomycin in vitro and in vivo against different bacterial strains localized in the urinary tract of paraplegic patients hospitalized for their rehabilitation in our Hospital. A total of 22 patients were studied and 24 treatments were carried out. A total of 33 organisms were isolated in the initial cultures. In all patients, the pattern of administration of the antibiotic was 4 g/day intramuscularly during 8 days. From the bacteriological standpoint, the results were excellent, although there was no question of clinical results due to the special circumstances of these patients. A sterilization of the urocultures was achieved in 20 of the 24 cases treated. No signs of intolerance or toxicity were observed in any of the patients upon administering the antibiotic.