• Symptom Relief (Resolved) [ Time Frame: Posttherapy Visit (Study Day 33-36) ] [ Designated as safety issue: No ]
• Clinical Success (Non-Relapse) or Failure (Relapse) [ Time Frame: Poststudy Telephone contact at 6 weeks ] [ Designated as safety issue: No ]
• Clinical Success (Non-Relapse) or Failure (Relapse) [ Time Frame: Poststudy Telephone contact at 3 Months ] [ Designated as safety issue: No ]
• Clinical Success (Non-Relapse) or Failure (Relapse) [ Time Frame: Poststudy Telephone Contact at 6 Months ] [ Designated as safety issue: No ]
• Total NIH-CPSI Score [ Time Frame: Screening/Admission, On-Therapy, Week 3, Week 4, Posttherapy (Study Day 33-36) ] [ Designated as safety issue: No ]

The purpose of this study is to compare the safety and effectiveness of levofloxacin 750 mg for 2 weeks or 750 mg for 3 weeks, compared to levofloxacin 500 mg for 4 weeks in the treatment of chronic prostatitis.

The optimal duration of treatment for chronic prostatitis remains unclear. Historically, therapy for chronic prostatitis with other classes of antibacterials resulted in poor outcomes and prolonged time taking the medication. Levofloxacin belongs to the quinolone class of antibacterials and has been used to treat chronic prostatitis with 500mg of levofloxacin taken orally once a day for 4 weeks. This multicenter, double-blind (neither the patient nor the physician knows whether drug or placebo is being taken, or at what dosage), randomized (patients are assigned different treatments based on chance) study is designed to see if giving levofloxacin at a higher dose for shorter periods of time is safe and effective in treating chronic prostatitis. Safety analyses will involve the examination of the incidence, severity, and type of adverse events and changes in physical findings including vital signs and clinical laboratory tests.

Patients will receive one of the following three dosing options: levofloxacin 750 mg orally administered once-a-day for 2 weeks followed by placebo once-a-day for two weeks for a total of 4 weeks, or levofloxacin 750 mg orally once-a-day for 3 weeks followed by placebo once-a-day for one week for a total of 4 weeks, or levofloxacin 500 mg orally once-a-day for 4 weeks.

Inclusion Criteria:

• Males 40 years of age or older
• A clinical diagnosis of chronic prostatitis as evidenced by the following two criteria: 1. Clinical signs and symptoms of prostatitis including a soft, tender prostate without noticeable nodularity with one or more of the following signs or symptoms: painful or difficult urination, suprapubic discomfort, painful ejaculation, low back pain, perineal discomfort, urinary frequency, urinary urgency or hesitancy, decreased urinary stream, urinary retention, pain on digital rectal examination, perineal tenderness or pain, fever, chills. 2. A history of chronic prostatitis as defined as: symptomatic prostatitis - a clinical diagnosis of prostatitis having been made for at least one previous episode that lasted four weeks, or two or more episodes during the previous twelve months

Exclusion Criteria:

• Any condition which may interfere with the evaluation of study drug including transurethral prostatectomy within six months of enrollment, the presence of a permanent transurethral catheter or a history of cystostomy or nephrostomy
• Taking hormone therapy
• Known prostatic carcinoma
• Allergy to levofloxacin, ofloxacin, ciprofloxacin, or other members of the quinolone class of antibacterials