Melanoma is rare among the Asian population. In Malaysia, there is little public awareness of melanoma compared to other types of cancer. Giant melanomas measuring more than 10 cm are rarely encountered and there are limited data available regarding this disease. We would like to report an unusual presentation of giant malignant melanoma of upper limb in a 62-year-old patient who presented with a five-month history of a progressively enlarging, painless mass on his left arm. This mass which measures 10 x 15 cm turned out to be a giant malignant melanoma of the left arm. To our knowledge, this is the largest melanoma of arm reported in Malaysia. Radiological findings were suggestive of soft tissue sarcoma with lung metastasis. Patient underwent wide local excision of left-arm mass and upper limb reconstruction. The diagnosis of malignant melanoma was made based on the final histopathology report. Despite aggressive treatment involving multidisciplinary units, it did not prevent the disease progression and patient succumbed five months after his presentation. Here, we present our experience in the management of this large malignant melanoma of the arm and to stress the sinister nature of melanoma.