Thirty-two patients were treated by ofloxacin on bacteriological documented infections. They were Enterobacterias: n = 15 (MIC less than or equal to 0.06 to 0.5 microgram/ml); Pseudomonas aeruginosa and Acinetobacter: n = 1 (MIC 0.5 and 4 micrograms/ml); Staphylococcus: n = 6 (MIC less than or equal to 0.06 to 4 micrograms/ml); Pneumococcus: n = 1; Mycoplasma: n = 1; Chlamydia psittaci: n = 2; Legionella pneumophila: n = 1; Rickettsias: n = 4 (three mediterranean fevers one query fever). Ofloxacin was given orally from 400 to 800 mg per day (5 to 15 mg/kg/day). It was used alone 26 times and on 6 occasions it was associated with rifampin on 6 staphylococcal infections. On 19 cases it was used after failure or intolerance of initial therapy. Thirty times it was the first antibiotic substance used. Results were good mainly: 1) on nine pneumonitis (enterobacterias: 4; Pneumococcus: 1; Mycoplasma: 1; Chlamydia: 2; Legionella: 1) during a mean duration of twenty days; 2) urinary infections (n:7) provoked by E. coli and Enterobacter cloacae (mean duration: 20 days); 3) 4 osteo-articular-infections (mean duration: 77 days); 4) Rickettsial infections (n:4) during a mean duration of 11 days. Results are particularly noteworthy because patients treated had severe infections: 12 bacteremias, 1 endocarditis and 1 purulent meningitis. None severe adverse effect was observed.