To provide an overview of the scientific and clinical studies underlying the most common vitamin and herbal preparations used in prostate and bladder cancer and evaluate the evidence behind them. A literature search was undertaken on PubMed using various keywords relating to the use of complementary and alternative medicine (CAM) in prostate and bladder cancer.Vitamin E and selenium supplementation can potentially have adverse effects by increasing the risk of prostate cancer. Initial clinical studies of pomegranate and green tea, investigating their chemotherapeutic properties in prostate and bladder cancer have yielded encouraging results. Curcumin, resveratrol, and silibinin have potential anticancer properties through multiple molecular targets; their clinical effectiveness in prostate and bladder cancer is yet to be evaluated. Zyflamend, like PC-SPES, is a combined CAM therapy used in prostate cancer. Acupuncture is popular among patients experiencing hot flushes who are receiving androgen-deprivation therapy for prostate cancer. Conclusive evidence for the use of CAM in prostate and bladder cancer is lacking and not without risk.