We report a case of an 88-year-old man with lentigo maligna melanoma. He noticed a blackish pigmented spot on his left mandibular angle twenty years ago. The lesion gradually enlarged reaching 5×3cm sized irregular pigmented patch expanding to his ear lobe. Two 1.6cm and 0.8cm sized nodules were also noted on the pigmented patch. An ulceration was noted on a large nodule. No palpable lmphnode was detected. Surgical resection of the lesion was carried out with 2cm-3cm wide margin. Lymphnode dessection and chemotherapy were not performed. Histological examination revealed a lentigo maligna melanoma with tumor thickness 7mm. A reverse transcription polymerase chain reaction (RT-PCR) was performed before the operation, detecting tyrosinase mRNA in the patient's blood. Total body examination disclosed that he had liver metastasis. The RT-PCR method for the detection of tyrosinase mRNA seems to be a useful tool for evaluation of melanoma with metastatic potential.