Background and Objective: Prulifloxacin, a broad-spectrum fluoroquinolone, is quantitatively transformed after oral administration into ulifloxacin, the active metabolite. On the basis of preclinical data suggesting that prulifloxacin is not likely to prolong the QT interval, a trial to assess the potential effects of prulifloxacin on QT and corrected QT (QTc) interval in humans was performed.