The efficacy of intravenous ofloxacin therapy (200 mg 12-hourly) followed, when appropriate, by oral administration of the same dose was evaluated in an open multicentre trial involving 185 patients in 31 French hospitals. Dosage adjustment was made for patients in renal failure. Infection was hospital-acquired in 35 cases, 53 patients required admission to an intensive care unit. The infections comprised septicaemia (n = 56), pneumonia (n = 18), bronchitis (n = 10), urinary tract (n = 78), female pelvis (n = 8), bone and joint (n = 5), skin and soft tissues (n = 10). The causative pathogens were: Staphylococcus spp. (n = 23), Streptococcus spp. (n = 11), Escherichia coli (n = 85), Haemophilus influenzae (n = 9), Klebsiella, Enterobacter or Serratia spp. (n = 21), Salmonella spp. (n = 22), Chlamydia spp. (n = 3), Legionella spp. (n = 1), Mycoplasma pneumoniae (n = 1) and miscellaneous Gram-negative bacilli (n = 17). All were ofloxacin-susceptible. Mean duration of therapy was 8.06 ( +/- 2.6) days for the i.v. and 14.8 ( +/- 14.39) days for the oral preparation. Clinical cure was achieved in 173 patients (93.5%). It is concluded that iv ofloxacin is an effective treatment for a range of infections due to susceptible organisms.