Gatifloxacin is a novel extended-spectrum fluoroquinolone with improved gram-positive and anaerobe coverage compared with older agents such as ciprofloxacin. It has good activity (but is slightly less active than ciprofloxacin) against Enterobacteriaceae. Gatifloxacin is generally 2- to 4-fold more active than ciprofloxacin against staphylococci, streptococci and enterococci and 4- to 16-fold more active than ciprofloxacin against anaerobes, including Clostridium and Bacteroides spp. In comparative clinical trials that included patients with lower respiratory tract, urinary tract, skin and soft tissue or gonococcal infections, clinical cure rates of > or = 89% were achieved with oral gatifloxacin 400 mg/day for 7 to 14 days. Data from a subset of North American patients included in a multinational trial showed that oral gatifloxacin 400 mg/day produced a significantly higher clinical cure rate than cefuroxime axetil 250 mg twice daily (89 vs 77%; p = 0.01) in patients with acute exacerbations of chronic bronchitis. The clinical efficacy of gatifloxacin was similar to that of clarithromycin or levofloxacin or ceftriaxone (with or without erythromycin) in the treatment of patients with community-acquired pneumonia. Oral gatifloxacin 400 mg/day showed clinical and bacteriological efficacy similar to that of levofloxacin in patients with skin and soft tissue infections. In patients with urinary tract infections, clinical cure and bacterial eradication rates achieved with a single 400 g oral dose of gatifloxacin were similar to those produced with ciprofloxacin. In a pooled analysis of tolerability data from trials that included 3021 patients treated with oral gatifloxacin 400 mg/day, the most commonly reported adverse events were nausea (8%), diarrhoea (4%), headache (4%) and dizziness (3%). The drug was reported to be well tolerated. Gatifloxacin does not appear to cause phototoxic effects.