Background: N,N,N-trimethyl phytosphingosine-iodide (TMP) was recently developed as an antitumor agent. Although phytosphingosine is an important molecule in many signaling pathways, the effects of TMP on melanogenesis have not been evaluated. Objectives: We evaluated the hypopigmentary effects and impact on melanogenesis-related signaling pathways of L-TMP treatment. Methods: Here, we examine the effects of TMP on melanogenesis and its related signaling pathways in Melan A cells and normal human melanocytes. Results: Our results show that melanin is significantly reduced in a dose-dependent manner in both cells following liposomal TMP treatment. We also investigated changes in the phosphorylation of extracellular signal-regulated kinase (ERK), which is related to the degradation of microphthalmia-associated transcription factor (MITF). Our results indicate that liposomal TMP treatment leads to the phosphorylation of ERK, which reduces both MITF and tyrosinase protein levels. Treatment with PD98059, an ERK pathway-specific inhibitor, restored liposomal TMP induced reductions in melanin, abrogated reductions in tyrosinase activity, and downregulated MITF and tyrosinase protein. Protein kinase C (PKC) activity and the PKC protein level were not altered by TMP treatment. Conclusion: These results suggest that the inhibitory effects of TMP on melanogenesis are due to MITF and tyrosinase downregulation via ERK activation.