The efficacy of norfloxacin in chronic bacterial prostatitis (CBP) was investigated in this prospective study. Twenty-two patients with CBP documented by sequential localization cultures were treated with norfloxacin 2x400 mg orally. The duration of the treatment ranged between 10 and 20 weeks (mean13.2 weeks). The results of sequential cultures were evaluated after six months and one year from the completion of therapy. Sixteen of the 19 evaluable patients (84 %) had sterile cultures in six months. In one year follow-up, this figure was 79 % (11 patients out of 14). These findings suggest that long-term norfloxacin can cure CBP.