Prostate cancer is one of the most common male malignancies worldwide, and benign prostatic hyperplasia (BPH) is a common cause of lower urinary tract symptoms in elderly men. Garlic (Allium sativum) has been known to have anti-inflammatory, anti-cancer and antioxidant effects. Owing to these effects, garlic and its preparations have been used for the treatment of prostate cancer and relief of BPH symptoms for decades. It is thought that the mechanism(s) through which garlic may show anti-cancer and anti-inflammatory effects should be investigated further. Several researchers are attempting to demonstrate the useful properties of garlic and its mechanism(s) of action. This review aims to present the current studies related with the effects of garlic in prostate diseases, namely prostate cancer and BPH.