Müllerianosis is the term used to designate lesions composed of an admixture of two or three types of müllerian-derivation glands in heterotopic location. In this report, we describe a case of incidental vaginal müllerianosis in a 59-year-old woman who underwent rectosigmoidectomy for rectal adenocarcinoma. In the vaginal cuff removed for neoplastic invasion, a separate multilocular mass measuring 1.5cm was found. The microscopic examination of the vaginal wall revealed endosalpingeal, endocervical and endometrial dilated or cystic glands with predominance of the endosalpingeal epithelium. Müllerian epithelium showed positivity for cytokeratins 7 and 8/18, high molecular weight cytokeratin, estrogen receptor alpha, and androgen receptor. The periglandular stroma was condensed and reactive for smooth-muscle actin, h-caldesmon, and CD10. To the best of our knowledge, a case of vaginal müllerianosis has not been previously reported. This lesion should be differentiated form vaginal adenosis and primary well-differentiated vaginal adenocarcinoma. The vagina should be added to the list of locations in which müllerianosis can be observed.