Since fosfomycin has behaved in vitro as a broad-spectrum antibiotic, an attempt has been made to evaluate this behaviour in controlled clinical study carried out at different Spanish hospitals. A total of 959 patients were treated for some of the following infectious clinical processes: gonococcal urethritis, typhoid fever, enterocolitis, acute and chronic urinary tract infections, osteomyelitis, chronic otorrhoea, septicaemia, meningitis, peritonitis, surgical and suppurative infections, bronchitis, pneumonia, pharyngoamygdalitis, burns, endometritis, ocular infection, whooping cough and nasal carriers of S. aureus. The results obtained as a function of the microorganism isolated in these clinical processes in percentage of clinical and bacteriological success have been 96% of the S. aureus infections, 95% of the Streptococcus sp. including S. pneumoniae, 90% of the N. gonorrhoeae infections, 94% of the E. coli infections including enteropatho-genic E. coli, 90% of the S. marcescens infections, 76% of the Proteus sp. infections, 72% of the Klebsiella-Enterobacter infections, 66% of P. aeruginosa infections and 78% of the S. typhi infections.