We report the case of a 57-year-old man with a malignant melanoma in the subunguinal region of his right thumb associated with the palpable axillary lymph nodes. Its metastasis was confirmed by fine needle aspiration biopsy cytology. Prognosis if a malignant melanoma is protean by its stage. Thus information regarding the axillary metastasis is mandatory for deciding the therapeutic plan. Fine needle aspiration biopsy cytology is a useful technique for diagnosing lymph node metastasis.