To asses the efficacy and the safety of ofloxacin as therapy of pneumonia caused by intracellular pathogens, 35 patients were studied (26 male, 9 female, mean age: 52.5 +/- 16.6 years). Causative pathogens were Chlamydia psittaci (n = 13), Legionella pneumophila (n = 10), Mycoplasma pneumoniae (n = 7) and Coxiella burnetii (n = 5). Ofloxacin was administered orally in 32 cases (200 mg b.i.d. in 80% of cases) and by I.V. route in 3 cases. All patients were cured without any side effects. In conclusion, ofloxacin appears, in our study, as an efficient therapy for these pneumonias. It could be considered as a valuable alternative to other antimicrobial agents with intra-cellular activity.