66 patients were given daily doses of ofloxacin between 400 and 800 mg for 10 days to 6 months. They were suffering from exacerbation of chronic bronchitis (15), soft tissue phlegmon (11), complicated urinary tract infections (7), bronchopneumonia (7), chronic osteomyelitis in exacerbation (8), chronic prostatitis in exacerbation (5), lower urinary tract infections (3), chronic otitis media (3), acute otitis (3), acute bronchitis (1), lung abscess (2) or liver abscess (1). Pathogens included Pseudomonas aeruginosa (24), Haemophilus influenzae (16), Proteus mirabilis (6), Escherichia coli (6), Enterobacter cloacae (6), Providencia stuartii (2), Serratia marcescens (2), Citrobacter diversus (1), Salmonella enteritidis (1), Acinetobacter anitratus (1), Staphylococcus aureus (1) and Streptococcus pneumoniae (1). In 35 patients (53%), several aggravating factors coexisted. MICs of ofloxacin ranged from less than or equal to 0.06 to 2 mg/L. Clinically, 65% of the patients were considered as cured, 17% improved and 18% failed to respond. Bacteriologically, pathogens were eradicated in 62%, persisted in 16% and relapsed in 22%. Adverse reactions included gastrointestinal disturbances (4), rash plus facial oedema (1), abnormal liver function (2) and leucopenia (1).