Mucinous carcinoma of the breast is a relatively rare, pure form accounting for 2% of all breast cancers. Pure mucinous carcinoma of the breast has a favorable prognosis. The common age is postmenopausal group. Here, we report a 30-year-old female patient diagnosed on cytology as mucinous carcinoma of the breast with lymph node metastasis and subsequently confirmed by histopathology. In 1 year follow-up, the patient did not show pulmonary or distant metastasis and received adjuvant chemotherapy at every 3 weeks interval.