Metastatic disease from a primary malignancy to the duodenum is extremely rare. Here, we report the first case of a recurrent vaginal squamous cell carcinoma that metastasized to the duodenum. Cytological and histopathological examinations were useful for the diagnosis of a recurrent vaginal cancer metastasizing to the duodenum. Primary vaginal cancer is a rare tumor, making up approximately 1%-2% of all gynecologic cancers and only 10% of all malignant neoplasms involving the vagina. 1 According to Cancer Statistics in Japan-2019, of 157,800 deaths due to female malignant neoplasms, 139 deaths (0.09%) were due to vaginal cancer. 2 Approximately 6,230 new cases of vaginal cancer associated with 1,450 deaths have been estimated for 2020 in the United States. 3 Squamous cell carcinoma (SCC) is the most common histopathological type (85%) followed by adenocarcinoma (10%-15%). 4 A population-based study from Denmark reported that 89% of women with vaginal SCC were positive for high-risk human papillomavirus (HPV). 5 Though vaginal cancer may invade locally and disseminate by hematogenous and lymphatic routes, 4 a metastasis to the duodenum is extremely rare. Only 1 case report of vaginal malignant melanoma with metastasis to the papilla of Vater can be found on PubMed. 6 Herein, we report a case of recurrent vaginal cancer metastasizing to the duodenum, for which cytological and histopathological examinations were useful for obtaining a diagnosis.