Abstract: In this paper, the ultrastructure of one case of amelanotic malignant melanoma(AMM)was described, which was mimic to squamous cell carcinoma clinically. The tumor cells showed great variation in their size and shape, arranged in groups or discretely. They might be divided into 3 types with different degrees of differentiation. No desmosome or tonofibril bundle was found, but some of them revealed granular or abortive melanosomes, Therefore, the tumor was quite different from squamous cell carcinoma, In discussion, the authors emphasized the importance of the electron microscopy of AMM. Finally its histogenesis was briefly discussed.