We present a 38-year-old premenopausal Japanese woman with invasive micropapillary carcinoma (IMC) of the left breast with minimal lymph node metastasis despite a huge size. The patient noticed a left breast mass and a bloody nipple discharge 2 years before admission. On admission, physical examination revealed a huge, elastic hard mass with skin ulcer 12x12 cm in diameter occupying the entire left breast. The patient underwent modified radical mastectomy with level III lymph node dissection, and the defect was reconstructed with a vertical rectus abdominis myocutaneous flap. Histopathologically, IMC comprised about 60% of the tumor, admixed with papillotubular and mucinous carcinoma. Only one of twenty-five lymph nodes had tumor metastasis. The patient remains well 8 months postoperatively without any signs of recurrence.