Purpose: Primary mucinous adenocarcinoma of the vagina is a rare disease which is characterized by aggressiveness and poor prognosis because of its rapid growth and recurrence, its frequent distant metastases, and its relative resistance to conventional treatment modalities including surgery, radiotherapy, and chemotherapy. We report a case of advanced stage primary mucinous adenocarcinoma of the vagina that showed a highly aggressive course and resistance to combination chemotherapy with paclitaxel and carboplatin. Case: A 46-year-old multigravid Japanese woman was admitted to our hospital to be treated for Stage IVb primary mucinous adenocarcinoma of the vagina. She had no history of in utero exposure to diethylstilbestrol. She was treated by two courses of neoadjuvant chemotherapy with tri-weekly paclitaxel and carboplatin, which were not effective. Subsequently, total pelvic exenteration with pelvic lymphadenectomy was performed. However, the disease progressed rapidly and the patient died five months after the initial treatment. Conclusion: Because of its rarity, little is known about the behavior of primary mucinous adenocarcinoma of the vagina. Additional data about patients with this rare tumor should be collected and analyzed in an attempt to elucidate its prognostic factors, characteristics, optimal treatment, and outcome.