Inclusion Criteria:

• Men with a diagnosis of HGPIN or ASAP in a minimum of 1 of 8 cores from a biopsy performed within six months of study entry.
• Prostate biopsy with a minimum of 8 cores performed within 6 months of study entry that shows no evidence of cancer.
• 30−80 years of age at the time of registration
• PSA ≤10 ng/ml
• Omnivorous diet
• Eastern Cooperative Oncology Group (ECOG) performance status 0−2
• Participants must have normal organ and marrow function as demonstrated by the following parameters being within normal institutional limits: complete blood count (CBC); liver function tests (liver functions tests [LFTs]; albumin, total and direct bilirubin, alkaline phosphatase, aspartic transaminase (AST), alanine transaminase (ALT), and total protein), PT/PTT, and LDH; serum creatinine <1.5 mg/dl or measured creatinine clearance 60 cc/min
• Absence of consumption of toremifene citrate, finasteride, testosterone, dehydroepiandrosterone (DHEA) or other testosterone-like supplements or medications which have known impact on PSA within 30 days of registration, or dutasteride within 90 days of registration
• Absence of consumption of any nutritional or herbal supplements, including herbs, green tea polyphenols and high-dose antioxidants
• No or low regular tea consumption (no more than 3 servings of hot tea or 6 servings of iced tea per week)
• Willing to discontinue current vitamin/mineral supplement use and substitute with a standard multivitamin supplement provided for the study
• Willing to use an effective method of contraception, if the partner is of child-bearing age, while on study
• Willing to comply with proposed visit and treatment schedule
• Able to understand and willing to sign a written informed consent document

Exclusion Criteria:

• Evidence of prostatitis or urinary tract infection; men may be enrolled 30 days after completion of treatment, provided all other eligibility criteria are met
• Current or prior history of prostate cancer or other malignancies (exceptions include non-melanoma skin cancer or other cancer with no evidence of tumor recurrence 5 years after definitive treatment)
• History of renal or hepatic disease, including history of hepatitis B, C or delta
• Participation in any other investigational study or use of any other investigational agents within 30 days of study entry
• History of allergic reactions attributed to tea or other compounds of similar chemical or biologic composition to Polyphenon E or the inactive components present in Polyphenon E and placebo capsules.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or any psychological, familial, sociological or other concomitant condition that would not allow adequate compliance with the study protocol