A multinational, multicentre, open, randomised study in hospitalised patients with pneumonia compared levofloxacin 500 mg twice daily with ceftriaxone 4 g i.v. once daily. Levofloxacin patients started on i.v. treatment and switched to oral on d 3-5 of therapy if signs and symptoms had improved. The minimum treatment duration was 5 d, except for treatment failure, and the median 8 d. The primary efficacy analysis was based on the per-protocol assessment of the clinical cure rate determined 2-5 d after the end of treatment in the per-protocol (PP) population (levofloxacin 127, ceftriaxone 139). Of 625 patients enrolled and randomized, 6 received no treatment, giving an intention-to-treat (ITT) population of 619 (levofloxacin 314, ceftriaxone 305). At the clinical endpoint, 2-5 d after the end of treatment, the cure rates for levofloxacin and ceftriaxone were similar in both the ITT (76% and 75%, respectively) and PP (87% and 86%, respectively) populations. Both drugs were well tolerated. Twice-daily levofloxacin 500 mg, either i.v. or as sequential i.v./oral therapy, was as effective as i.v. once-daily ceftriaxone 4 g in the treatment of hospitalized patients with pneumonia and offers the advantage of sequential therapy.