Infection of the prostatic gland tissue is frequent, affecting from 4 to 5% of men according to anatomical studies. The classical distinction between acute and chronic prostatitis still too often suggests different diseases, whereas chronic prostatitis in fact is the clinical expression of an initial acute or subacute infection for lack of diagnosis and therefore of an appropriate and sufficiently prolonged treatment. In both acute and chronic prostatitis the pathogens are the same: E. coli at all ages, organisms causing urethritis in young men, Gram-negative and often multiresistant bacilli in iatrogenic infections. Fluoroquinolones, which are active against most of these bacteria and are present in high concentrations in the prostate, are for the moment among the most effective antibacterial agents. But unless they are prescribed at an early stage and for long periods prostatitis may remain a desperately chronic disease.