The prevalence of prostate cancer, a kind of cancer that affects males, is rising globally. The side effects of the cancer treatment lower patients' quality of life because it is harmful to healthy cells. This has spurred a lot of research to identify alternative treatments, including natural substances-derived anticancer drugs. Red yeast rice, the rice fermentation by the Monascus purpureus fungus, is one of the natural components with anticancer action. The purpose of this study is to evaluate the potential of different red yeast rice extracts to suppress the proliferation of prostate cancer cells. The MTS assay  was used to test the ethanol, ethyl acetate, and n-hexane extracts' toxicity against the DU145 prostate cancer cell line at different concentrations.Research findings show that the n-hexane extract has the best cytotoxicity with an IC₅₀ value of 138.9 ± 45.46 μg/mL followed by ethyl acetate and ethanol extracts with IC₅₀ values of 207.916 ± 41.75 μg/mL and 649.426 ± 28.05 μg/mL, respectively. The flavonoid and quinone components in the n-hexane red yeast rice extract are assumed to be the source of its mild cytotoxicity.