The case of a female who had severe, rare, terminal breast mucinous carcinoma (BMC) and failed to receive surgery and chemotherapy was reported. The patient was diagnosed with pure BMC (ER++, PR++, CerbB-2-, and Ki-67 10%) accompanied with bilateral lungs, bilateral chest walls with skin ulcer (D = 14 cm), lymph nodes of bilateral armpits, and right supraclavicular metastases. ECOG (Eastern Cooperative Oncology Group) and NRS (Numeric Rating Scale) pain scores were 4 and 6, respectively. Because the patient refused traditional chemotherapy and radiotherapy on religious grounds, an herbal medicine containing Panax ginseng, Agrimonia pilosa, and white flower Patrinia herb was administered; extensive nursing for tumor debridement was also provided. Quality of Life (QOL) improved and pain reduced. Tumor-bearing survival time was prolonged. The present case dictates that herbal extract medicines and supportive treatment can be helpful for uncommon severe BMC as an appropriate alternative treatment.