In a multinational, open, randomised, controlled clinical study, 474 hospitalised patients with moderate or severe infections were treated with sequential regimens of ofloxacin or ciprofloxacin, Ofloxacin 400 mg once daily or ciprofloxacin 200 mg twice daily were given intravenously for at least 3 days followed by oral treatment,vith ofloxacin 400 mg once daily or ciprofloxacin 500 mg twice daily. Overall cure rates of 86.8% (85.7%) in the ofloxacin group and 89.6% (89.5%) in the ciprofloxacin group were achieved in the intention-to-treat analysis (per protocol analysis). The overall bacteriological response rate (ofloxacin 89.5%, ciprofloxacin 89.0%) was comparable to the clinical cure rate. Both drugs were well tolerated and adverse events were rarely observed. It is concluded that ofloxacin and ciprofloxacin can be used successfully in the treatment of hospitalised patients with aerobic gram-positive and gram negative infections. Ofloxacin has the advantage of a once-daily regimen, compared to the twice-daily regimen with ciprofloxacin.