Abstract: Cruciferous vegetables belong to the plant family that has flowers with four equal-sized petals in the pattern of a crucifer cross1,2. These vegetables are an abundant source of dietary phytochemicals, including glucosinolates and their hydrolysis products such as indole-3-carbinol (I3C) and 3,39-diindolylmethane (DIM). By 2013, the total number of natural glucosinolates that have been documented is estimated to be 1323. Recently, cruciferous vegetable intake has garnered great interest for its multiple health benefits such as anticancer, antiviral infections, human sex hormone regulation, and its therapeutic and preventive effects on prostate cancer and high grade prostatic intraepithelial neoplasia (HGPIN). DIM is a hydrolysis product of glucosinolates and has been used in various trials. This review is to provide an insight into the latest developments of DIM in treating or preventing both prostate cancer and HGPIN.