Equine melanocytic tumours may be either a benign or malignant skin disease. They commonly involve the skin of grey horses. There are no reports of mid-tail melanocytoma with sudden malignant transformation. Partial tail amputation was used to resect a melanocytic tumour mass from the mid-tail of a 16-year-old bay Irish Draught (ID) horse. There was no evidence of significant re-growth or complications at a 6-month post operative examination.