N-Phenylthiourea is a tyrosinase inhibitor and building block. It increases the susceptibility of SK-MEL-188 melanoma cells in melanogenesis-inducing conditions to γ-radiation-induced cytotoxicity when used at a concentration of 0.01 μM. N-Phenylthiourea has been used as a precursor in the synthesis of compounds with antibacterial and antifungal activities. It has also been used as a genetic marker for taste because only some people detect it as a bitter taste.