The literature on the penetration of ofloxacin from blood to respiratory tissue and secretions in patients is reviewed. In patients with acute purulent exacerbations of chronic bronchitis ofloxacin has a Cmax value in sputum of 2.7 mg/l after a 400 mg oral dose, 6.1 mg/l after 600 mg and 6.3 mg/l after 800 mg. Penetration from blood to sputum varied from 80 to 100%. The concentration of ofloxacin in bronchial aspirate, 1 to 6 h after a single oral dose of 400 mg, varied between 1.1 and 4.5 mg/l. The ratio between simultaneous mean bronchial aspirate and serum concentrations ranged between 0.53 in the second hour and 0.92 in the fourth hour. Ofloxacin concentrations in bronchoalveolar lavage fluid following an oral dose of 200 mg twice daily for at least four days amounted to 8.3 mg/l with a corresponding serum concentration of 1.7 mg/l five hours after the last dose. The distribution ratio between lavage fluid and serum was 4.9. The lung tissue penetration of ofloxacin after a dosage of 200 mg twice daily, reached a mean tissue plasma concentration ratio of 3.5 +/- 0.4 for healthy tissue and 3.9 +/- 0.4 for diseased tissue. Ofloxacin reaches high intracellular concentrations in polymorphonuclear leucocytes, alveolar macrophages, epithelial cells and fibroblasts. It is likely that these concentrations will have a sustained inhibitory and bactericidal activity against most potential respiratory pathogens including: Haemophilus influenzae, Branhamella catarrhalis, Gram-negative bacilli, Staphylococcus aureus, Legionella pneumophila, Chlamydia spp. and Coxiella burnetti.